Heavy Ball Bounce: Understanding Mass, Density, and Momentum in Physics

How does mass affect a ball’s bounce. What role does density play in object behavior. Why do heavy balls often bounce less than light ones. How do air friction and surface area influence falling objects. What factors determine a ball’s rolling behavior.

The Physics Behind Ball Bouncing: Mass, Density, and Energy

When exploring the fascinating world of physics, understanding how different balls bounce can provide valuable insights into fundamental concepts. Let’s delve into the intricate relationship between mass, density, and energy in the context of bouncing balls.

The Role of Mass and Density

Mass and density are crucial factors that determine how an object behaves when dropped or bounced. But what exactly is the difference between these two properties?

• Mass: The amount of matter in an object
• Density: The mass of an object per unit volume

A tennis ball, for instance, has a relatively small mass concentrated in a compact space, making it light. In contrast, a lead ball of the same size would have a much larger mass in the same volume, resulting in significantly higher density.

Energy Conversion in Bouncing Balls

When a ball is dropped, it undergoes a series of energy conversions. How does this process work?

1. As the ball falls, it gains kinetic energy due to gravity
2. Upon impact with the ground, this energy is converted into upward energy
3. The upward energy must then overcome gravity to propel the ball back into the air

Interestingly, the size and drop distance being equal, a heavier, denser ball will fall with more energy than a lighter one. This is because while gravity accelerates all objects equally regardless of mass, momentum is calculated as mass multiplied by velocity. Consequently, the denser ball possesses greater momentum and kinetic energy as it strikes the ground.

The Surprising Bounce Behavior of Heavy Balls

Given that heavier balls have more energy upon impact, one might assume they would bounce higher than lighter balls. However, this isn’t always the case. Why do heavy balls often bounce less than their lighter counterparts?

The answer lies in energy dissipation. When a heavy ball impacts the ground, it’s more likely to lose energy into the surface due to its increased mass and momentum. This energy loss results in a lower bounce height compared to lighter balls, despite the initial higher energy.

It’s important to note that the bouncing behavior can vary depending on the surface and material of the ball. For example, bowling balls can bounce quite impressively on concrete surfaces, defying our usual expectations.

Rolling Dynamics: Light vs Heavy Balls

The behavior of balls doesn’t stop at bouncing. How do heavy balls roll compared to light ones? Understanding this can provide valuable insights into momentum and energy conservation.

Generally, a light ball requires less energy to start rolling. However, once in motion, a heavy ball will typically roll faster and for a longer distance than a light ball, provided it has more momentum. This phenomenon is similar to why large semi-trucks take much longer to stop compared to small cars.

In animation or visual effects, the representation of rolling heavy balls can vary based on artistic choices. Some may prefer to show a heavy ball dropping almost straight down with minimal roll to emphasize its weight, while others might depict a longer roll to showcase its momentum.

Air Resistance and Its Impact on Falling Objects

When discussing the behavior of falling objects, it’s crucial to address the role of air resistance. Why do some objects like feathers or sheets of paper seem to float down rather than drop quickly?

Contrary to popular belief, gravity exerts the same force on all objects regardless of their mass. The key factors that cause some objects to fall more slowly are:

• Air friction
• Air density
• The object’s surface area

These factors explain why balloons, feathers, and sheets of paper descend gently to the ground instead of dropping rapidly like denser objects.

The Curious Case of Balloons

Balloons present a particularly interesting case study in object behavior. Why do they float down so lightly? The answer lies in their composition and structure:

• Balloons contain much more air inside than the rubber that forms their outer layer
• The rubber is distributed over a large area, resulting in extremely low density
• This low density, similar to that of air, causes the balloon to descend slowly

The balloon’s behavior is further evidenced by the difficulty in throwing or hitting it far distances, as its density is so close to that of the surrounding air.

Surface Area and Air Interaction: Paper and Feathers

While balloons float due to their low density, paper and feathers exhibit a different mechanism for their slow descent. How do these objects interact with the air around them?

The “floating” behavior of paper and feathers is primarily due to their wide surface areas and light weight. These characteristics cause them to glide over the air, much like a hang glider, rather than cutting through it like denser objects.

An interesting experiment to demonstrate this principle involves dropping a piece of paper in different orientations. When dropped flat, it will float down slowly. However, if dropped on its edge, it will fall much more quickly, illustrating the significant impact of surface area on air resistance.

Momentum and Its Role in Object Behavior

Momentum plays a crucial role in determining how objects move and interact with their environment. But what exactly is momentum, and how does it affect the behavior of different objects?

Momentum is defined as the product of an object’s mass and its velocity. This property explains why denser objects are better at overcoming air resistance – they possess more momentum. The relationship between momentum and object behavior manifests in several ways:

• Heavier objects, once in motion, tend to maintain their movement for longer periods
• Denser objects can more easily overcome air resistance due to their greater momentum
• The momentum of an object influences its impact force upon collision

Understanding momentum is key to predicting and explaining the behavior of objects in various scenarios, from sports to industrial applications.

Practical Applications of Ball Physics

The principles governing ball behavior have numerous practical applications across various fields. How can understanding these concepts benefit real-world scenarios?

Sports and Athletics

In sports, the behavior of balls is crucial to game dynamics and strategy:

• Golf: Club design and ball composition are optimized based on principles of momentum and air resistance
• Tennis: The bounce and speed of tennis balls are carefully controlled to maintain consistent gameplay
• Basketball: The material and inflation of basketballs are regulated to ensure proper bounce and handling characteristics

Engineering and Design

Understanding ball physics is essential in various engineering applications:

• Automotive Design: Ball bearings rely on principles of momentum and friction to function efficiently
• Construction: The behavior of wrecking balls is based on the principles of mass, momentum, and energy transfer
• Manufacturing: Many industrial processes involve the controlled movement of spherical objects

Animation and Visual Effects

In the world of animation and visual effects, accurately representing the physics of different objects is crucial for creating believable and engaging content:

• Character Animation: Understanding how objects of different masses move helps in creating realistic character movements
• Special Effects: Simulating the behavior of various objects in computer-generated environments requires a solid grasp of physics principles
• Game Design: Physics engines in video games rely on accurate representations of object behavior for realistic gameplay

Experimental Approaches to Understanding Ball Physics

Exploring the principles of ball physics through hands-on experiments can provide valuable insights and reinforce theoretical understanding. What are some simple experiments that can demonstrate these concepts?

Gravity and Free Fall Experiment

To demonstrate that gravity affects all objects equally regardless of mass:

1. Choose two objects of significantly different weights (avoid sharp or fragile items)
2. Hold the objects at the same height
3. Drop both objects simultaneously
4. Observe that they hit the ground at the same time

This experiment illustrates that gravity’s acceleration is constant for all objects, regardless of their mass.

Bounce Height Comparison

To compare the bouncing behavior of balls with different masses:

1. Select balls of similar size but different masses (e.g., a ping pong ball, a rubber ball, and a steel ball)
2. Drop each ball from the same height onto a hard, flat surface
3. Measure and compare the heights of the first bounce for each ball
4. Observe how the bounce heights differ and relate to the balls’ masses

This experiment can help visualize how mass and energy transfer affect bounce height.

Rolling Distance Test

To explore how mass affects rolling behavior:

1. Choose balls of similar size but different masses
2. Create a ramp with a smooth, flat surface
3. Release each ball from the top of the ramp
4. Measure the distance each ball rolls after leaving the ramp
5. Compare the results and discuss how mass influences rolling distance

This experiment demonstrates the relationship between mass, momentum, and rolling behavior.

Advanced Concepts in Ball Physics

While the basic principles of ball physics are accessible to most, there are more advanced concepts that provide deeper insights into object behavior. What are some of these advanced topics?

Coefficient of Restitution

The coefficient of restitution is a measure of the “bounciness” of an object. It’s defined as the ratio of the velocity of separation to the velocity of approach in a collision. This concept is crucial in understanding why different materials bounce differently:

• A coefficient of 1 indicates a perfectly elastic collision (no energy loss)
• A coefficient of 0 indicates a perfectly inelastic collision (maximum energy loss)
• Most real-world collisions have coefficients between 0 and 1

Angular Momentum

Angular momentum is a property of rotating objects that affects their behavior:

• It’s conserved in the absence of external torques
• Affects the stability and motion of spinning objects
• Crucial in understanding the behavior of balls in sports like baseball or cricket

Fluid Dynamics

For objects moving through air or water, fluid dynamics principles come into play:

• Bernoulli’s principle explains lift in objects like frisbees or curved balls in sports
• Reynolds number helps predict the transition between laminar and turbulent flow around objects
• Understanding these concepts is crucial for designing aerodynamic sports equipment and vehicles

These advanced concepts provide a more complete picture of object behavior, allowing for more accurate predictions and applications in various fields.

Twins & Tangents: Class 1 – Week 4

So last week, we talked about how the effects of Gravity, Momentum,
Friction, and Density affects a basketball/soccer ball. We learned
that as a ball bounces, the effects of its kinetic energy vs. gravity
is what gives that signature tapered arc in the bounces, and that a
ball has height degradation, which means that each bounce causes
the ball to lose energy, so that each consecutive bounce will be
smaller that the previous one, unless it somehow gains energy, like
from falling off a ledge.

Now that we know all that, how do we then apply it to balls of
different weights? What is it that really makes the difference
between a ping pong ball and a cannonball? Is it size? A bowling
ball weighs more than a tennis ball, but on the flip side, a small
lead ball weighs a lot more than a large beach ball. So that’s not
it. Maybe it’s gravity pulling on one ball more than the other? You
can actually experiment with this yourself by taking two objects of
different weights (preferably not something sharp or fragile) and
dropping them at the same time. You’ll find that no matter the
difference in weight, both objects will hit the ground at the same
time. Gravity has the same pull on any object, no matter it’s size
or weight. But then why do balloons, feathers, and sheets of paper
float down to the ground instead of dropping? The reason for this is
air friction, air density, and the surface area of an object which
we’ll discuss a bit further down.

The answer to our question is Mass and Density. An object’s mass is what
determines how heavy it is, and consequently, how its arcs and height
degradation is affected. Density is what causes different objects of
the same size to weigh more or less than each other. A tennis ball has
a small amount of mass in a relatively small amount of space, making it
light, whereas a tennis ball sized lead ball has a large amount of mass
in a small amount of space, making it very dense.

Mass & Density on a Bouncing Ball

So how do these affect the bouncing ball? As I mentioned last week,
when a dropped ball bounces, the downwards energy it got from falling
(gravity) gets converted into upwards energy which then has to fight
against gravity to be able to get the ball into the air again. With
the size and drop distance of both a light and heavy ball kept constant,
the heavier, denser ball will fall with more energy (not to be confused
with more speed). The reason for this is because gravity accelerates
all things equally, regardless of mass, and momentum = mass * velocity.
So the denser ball has more momentum and more kinetic energy as it
strikes the ground. In fact, the reason why denser objects overcome air
drag better is that they have more momentum.

With that information, you would think that a heavy ball would bounce
higher than a light ball because of the increased momentum and energy.
Depending on the surface and material of the ball, it definitely can
(Bowling balls on concrete can bounce pretty well). But the reason why
heavy balls often bounce less is that when they impact, they are more
likely to lose energy into the ground plane because of their increased
mass and momentum.

But now what about ball roll? How do heavy balls roll compared to light
balls? In general, a light ball doesn’t take much energy to start
rolling, but a heavy ball will roll faster and longer than a light
ball, the more momentum it has. This is the same reason a large
semi truck takes forever to stop compared to a small car. Be sure to
ask your mentor what kind of rolling they like to see on the heavy
balls. Some mentors, like mine, wanted to see a heavy ball drop almost
straight down with no roll to emphasize the weight, but others like
Beau’s wanted to see a heavy ball with a longer roll to show momentum.

Light Balls VS Balloons

I bet you thought I forgot about this topic! Nope. I’ve left it for
last because it doesn’t really have anything to do with light vs heavy
balls, but is still kind of an important topic to talk about. As I
mentioned before, the reason why light balls drop and balloons, feathers,
and sheets of paper float down to the ground isn’t because of gravity
pulling things down with different amounts of force, but because of air
friction, air density, and the surface area of an object.

Balloons float down so lightly because they have so much more air inside
them than they have the rubber that makes them, and the rubber is
distributed over such a large area that its density is extremely low,
causing it to float down. You can see that a balloon has a density similar
to air by the fact that you can’t throw it or hit it very far. Now Paper
and feathers “float” because their wider surface areas and light weight
cause them to glide over the air like a hang glider would, not because of
air density. If you were to drop a piece of paper on it’s edge, you’ll see
that it slices through the air and drops pretty quickly, or if you crumple
it, it will drop like any other object.

Thank you for taking the time to read my post. I hope it’s been helpful,
and as always, if you have any comments, questions or suggestions,
you’re more than welcome to leave a comment or send either Beau or
me a message on AM.

Collisions and Momentum: Bouncing Balls – Lesson

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Quick Look

Grade Level: 8
(7-9)

Time Required: 45 minutes

Lesson Dependency: None

Subject Areas:
Physical Science, Physics

Summary

As a continuation of the theme of potential and kinetic energy, this lesson introduces the concepts of momentum, elastic and inelastic collisions. Many sports and games, such as baseball and ping-pong, illustrate the ideas of momentum and collisions. Students can use the associated activities to explore these concepts by bouncing assorted balls on different surfaces and calculating the momentum for each ball.
This engineering curriculum aligns to Next Generation Science Standards (NGSS).

Engineering Connection

Crunch! That is the sound that you hear when two cars crash into each other. This unnerving sound can be a good thing if it is the sound of a wonderful safety innovation developed by engineers, called the crumple zone. Mechanical engineers consider momentum and collisions when designing vehicles. A crumple zone is designed into motor vehicles to absorb the main impact of the energy being transferred during a crash, so the people inside don’t get hurt. Airbags are another engineering safety improvement to protect passengers from the impact of collisions.

Learning Objectives

After this lesson, students should be able to:

• Calculate the momentum of a moving object.
• Recognize that momentum is proportional to mass and velocity.
• Explain that in a closed system, momentum is conserved in both elastic and inelastic collisions.
• Describe how collisions and momentum play an important role in the design of safe automobiles.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science,
technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN),
a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics;
within type by subtype, then by grade, etc.

NGSS: Next Generation Science Standards – Science

NGSS Performance Expectation
HS-PS2-2. Use mathematical representations to support the claim that the total momentum of a system of objects is conserved when there is no net force on the system. (Grades 9 – 12) Do you agree with this alignment? Thanks for your feedback!
Click to view other curriculum aligned to this Performance Expectation
This lesson focuses on the following Three Dimensional Learning aspects of NGSS:
Science & Engineering Practices	Disciplinary Core Ideas	Crosscutting Concepts
Use mathematical representations of phenomena to describe explanations. Alignment agreement: Thanks for your feedback!	Momentum is defined for a particular frame of reference; it is the mass times the velocity of the object. Alignment agreement: Thanks for your feedback! If a system interacts with objects outside itself, the total momentum of the system can change; however, any such change is balanced by changes in the momentum of objects outside the system. Alignment agreement: Thanks for your feedback!	When investigating or describing a system, the boundaries and initial conditions of the system need to be defined. Alignment agreement: Thanks for your feedback!

Common Core State Standards – Math

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International Technology and Engineering Educators Association – Technology

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  Students will develop an understanding of the relationships among technologies and the connections between technology and other fields of study.
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State Standards

Colorado – Math

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More Curriculum Like This

Bouncing Balls: Collisions, Momentum & Math in Sports

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Bouncing Balls: Collisions, Momentum & Math (for High School)

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Exploring Linear Momentum

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Puttin’ It All Together

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Introduction/Motivation

The concept of momentum is often used in sports. An announcer might say, “The Denver Nuggets really have some momentum going into the fourth quarter!” or a newspaper headline might read, “The Colorado Avalanche pick up momentum!” What this means is that the team is sticking together and moving ahead as a whole rather than playing as individuals and not getting anywhere. In the engineering and physics world, momentum refers to the quality of motion that an object has, and it depends on the mass and velocity of the object:

Momentum = mass x velocity

So, if the Colorado Avalanche were all skating together in a close group at a fast speed, they would have a lot of momentum, physically.

Show the class a ping-pong ball and a golf ball. Although they are about the same size, the golf ball is heavier. Explain that if you threw each ball the same speed, the golf ball would have greater momentum. This becomes painfully obvious with an example. Ask the students if they have ever played “dodge ball” or a similar game. Ask the students if they would rather play with the ping-pong ball or the golf ball. As students groan at the thought of getting hit with a golf ball, explain that the reason it would hurt more is because it would have substantially more momentum than a ping-pong ball. In this case, more momentum is due to the greater mass (weight) of the golf ball, and the momentum of the golf ball would translate into a big bruise on your leg!

Lesson Background and Concepts for Teachers

A brief review of the concepts of potential and kinetic energy (covered in detail in the previous lesson) and momentum, is provided below:

Potential energy is the energy that an object has because of its position. Potential energy can also be thought of as stored energy — energy that an object has, as an inherent characteristic, but is not in use. It is sometimes called gravitational potential energy (PE). It can be expressed mathematically as follows:

PE = mass x g x height

where PE is the potential energy measured in Joules (J) and g is the acceleration due to gravity. At sea level g = 9.81 meters/sec². An example of potential energy is a book resting on the edge of a table. If you were to nudge it off the edge of the table the book would fall to the floor and make a loud noise. This is an expression of kinetic energy. Kinetic energy is the energy an object has because of its motion; any object that is moving has kinetic energy. The falling book in this example is an illustration of kinetic energy. The kinetic energy depends on both mass and velocity and can be expressed mathematically as follows:

Momentum can be thought of as “mass in motion” and is given by the expression:

Momentum = mass x velocity

The amount of momentum an object has depends both on its mass and how fast it is going. For example, a heavier object going the same speed as a lighter object would have greater momentum. Sometimes, when objects collide into each other, momentum can be transferred from one object to another. There are two types of collisions that relate to momentum: elastic and inelastic. In a closed system, which means that there are no external forces acting on the objects that collide, both types of collisions follow the Law of Conservation of Momentum, which states “the total amount of momentum before a collision is equal to the total amount of momentum after a collision.”

Watching a billiards game is an ideal place to observe ball collisions.copyright

Copyright © Microsoft Corporation 1983-2001.

In an elastic collision, not only is momentum is conserved, but also kinetic energy. The total kinetic energy of the system (which includes the objects that collide) is the same before and after the collision. An example of an elastic collision would be a super-bouncy ball. If you were to drop it, it would bounce all the way back up to the original height at which it was dropped. Another elastic collision example can be seen while playing a game of pool. Watch a moving cue ball hit a resting pool ball. At impact, the cue ball stops, but transfers all of its momentum and kinetic energy to the other ball, resulting in the hit ball rolling with the initial speed of the cue ball.

In an inelastic collision, momentum is conserved, but the total kinetic energy of the system is not conserved. When the collision occurs, some kinetic energy is transferred to another kind of energy such as heat or internal energy. A dropped ball of clay demonstrates an extremely inelastic collision. It does not bounce at all and loses its kinetic energy. Instead, all the energy goes into deforming the ball into a flat blob.

In the real world, there are no purely elastic or inelastic collisions. Even though rubber balls, pool balls (when hitting each other), and ping-pong balls may be assumed extremely elastic, there is still some bit of inelasticity in their collisions. If there were not, rubber balls would bounce forever. Refer to the Bouncing Balls: Collisions, Momentum & Math in Sports activity to have students investigate principle of conservation of momentum regarding elastic and inelastic collisions. For an extra challenge, refer to the Bouncing Balls: Collisions, Momentum & Math (for High School) activity. The degree to which something is elastic or inelastic is usually found experimentally.

The following demonstration shows momentum in action for an elastic collision. This demonstration is difficult to get right the first time, so practice a few times before presenting it to the class. First, bounce the ping-pong ball on the floor by dropping it from shoulder height. This works best on a tile floor. If your classroom is carpeted, bounce the balls onto a cinder block or a large brick placed on the carpet. Have a student volunteer mark on the board how high it bounced. Next, drop the golf ball from the same height and mark how high it bounced. Then, hold the golf ball and the ping-pong ball together, with the ping-pong ball directly on top of the golf ball. Drop them both and watch as the ping-pong ball bounces as high as 10 feet.

For a conservation of momentum demonstration, a ping-pong ball is held on top of a golf ball and they are dropped together.copyright

Copyright © Matt Lundberg and Chris Yakacki, ITL Program, University of Colorado at Boulder

At the bottom of the fall, students should understand that the golf ball has more momentum than the ping-pong ball. The trick to what happens is momentum from the golf ball transfers to the ping-pong ball. When the golf ball strikes the floor, it bounces up and collides with the ping-pong ball. This action transfers the greater momentum of the golf ball to the ping-pong ball, which responds by rising faster and higher. And, since the golf ball transfers much of its momentum to the ping-pong ball, the golf ball hardly bounces up at all. This demonstration illustrates conservation of momentum, which states that momentum may be transferred from one object to another, but the total momentum must stay the same.

Another way to look to understand collisions is through Newton’s 3rd Law, which tells us that “for every action, there is an equal and opposite reaction”. When the golf ball hits the floor, the force exerted on the floor by the golf ball is equal and opposite to the force exerted on the golf ball by the floor. This causes the golf ball to bounce and move upwards. When the golf ball collides with the ping-pong ball, the force exerted on the ping-pong ball by the golf ball is equal and opposite to the force exerted on the golf ball by the ping-pong ball. As we know, the golf ball (due to its larger weight) has more momentum than the ping-pong ball, so it transfers momentum to the ping-pong ball, and so the ping-pong ball goes higher in this scenario than if it was dropped alone (no collision). Remember, based on the Law of Conservation of Momentum, after the collision between the golf ball and the ping-pong ball, the total momentum of the system is conserved. This means that if you added the momentum of the two balls before the collision and added the momentum of the two balls after the collision, the total would be the same.

Engineers consider momentum when designing vehicles for safety. In a head-on collision, the front end of a car is designed to crumple, making the collision inelastic. It takes energy to crumple the front of the car and this is what absorbs some of the impact. This makes the crash less severe for anyone that is in the car. Instead of absorbing the full force of the crash, the passengers are cushioned by the inelastic collision. (Note: This “cushion” is not as comfortable as a pillow, but it will save lives during accidents.)

Engineers also consider momentum when designing brakes for vehicles. Heavy trucks and race cars require powerful braking systems to stop. Have you ever wondered why drag racing cars have parachutes to stop them? It is because conventional brakes are not powerful enough to stop them in a limited distance. These cars go so fast that their momentum is too great for regular brakes to be sufficient.

Associated Activities

Lesson Closure

With the entire class, discuss why different sports use different balls. The students may have found that a golf ball has a more elastic collision than a baseball. This is because in a game, a golf ball must be hit a very long distance from the tee to the hole. On the other hand, if a baseball had a very elastic collision, almost every ball could be hit out of the park. That would not make for a very interesting game, would it? The choice of balls used in other sports can be explained with similar explanations.

Engineers address vehicular safety by studying collisions. The airbag is a recent safety addition to automobiles. If you tried to bounce an airbag do you think it would have a more elastic or inelastic collision? (Answer: Inelastic.) A similar effect can be seen in a ball of clay. Instead of bouncing, the energy is used up in deforming the clay (or airbag). A combination of characteristics makes an airbag a good safety device; using up energy to deform the bag instead of the driver’s body is one of them. Other factors that help are distributing the force over a large area and time.

Vocabulary/Definitions

conservation of momentum: The amount of momentum in a system remains the same after a collision.

elastic collision: A collision in which all of the momentum is conserved. For example, a ball that bounces back up to its original height.

energy: The capacity to do work.

inelastic collision: A collision in which the kinetic energy is not conserved. For example, a ball that only bounces partially to its original height.

momentum: Mass in motion.

Assessment

Pre-Lesson Assessment

Voting: Ask the students to vote on the following question.

• Which has more momentum, a rolling bowling ball or ping-pong ball, going the same speed? (Answer: Bowling ball, because it has more mass.)

Brainstorming: In small groups, have the students engage in open discussion. Remind students that no idea or suggestion is “silly.” All ideas should be respectfully heard. Ask the students:

• What factors determine how much momentum an object has? (Answer: Mass and velocity. Answers such as, size and density, or if an object is dropped, are acceptable answers because they can influence both mass and velocity.)

Post-Introduction Assessment

Discussion Question: Ask the students and discuss as a class:

• How could a ping-pong ball have enough momentum to stop a moving bowling ball? (Answer: If the ping-pong ball was going really, really fast.)

Lesson Summary Assessment

One and Done: Ask the students to think of a sport that involves a collision and transfer of momentum, and raise their hands (or indicate thumbs up) when they have an example. (Possible answers: Baseball, pool, bowling, football [i.e., field goal or punt, etc.]). Call on students at random to state their answer (the sport and description of the collision). Students put their hands down once they’ve contributed an answer. No repeat answers permitted.

Calculations: Ask students to complete the following calculations to test their new knowledge of momentum:

• Let’s calculate the momentum of the golf ball in the above example. If the golf ball has a mass of .05 kg, and a velocity of 15 m/s, then what is its momentum? (Answer: momentum= .05 kg*15 m/s= 0.75 kg m/s)
• What if we were now dropping a rock instead? With a momentum of 220 kg m/s, and a velocity of 20 m/s, what is the mass of the rock? (Answer: m=momentum/velocity=220/20= 11 kg)

Toss-a-Question: Ask students to independently think of an answer to each of the questions below and write it on a half sheet of paper. Have students wad up and toss the paper to another team member who then adds their idea. After all students have written down ideas, have them toss the paper wad to another team, who reads the answers aloud to the class. Discuss answers with the class.

• How does the elasticity and inelasticity of balls affect sports?
• Why are baseballs not made out of super-elastic rubber? (Answer: If baseballs were made of rubber and were super-elastic, everyone could hit a home run easily.)
• Why are pool balls not made of clay? (Answer: If pool balls were made of clay it would be almost impossible to move the balls across the table.)

Lesson Extension Activities

Have the students further explore the mechanics of hitting a baseball with a bat by visiting this website: https://www.exploratorium.edu/baseball/features/how-far-can-you-hit-one.html. This website covers the concept of momentum and collisions and how it relates to baseball in an easy-to-understand and interesting account of the mechanics of baseball. Visit the Exploratorium’s baseball index at https://www.exploratorium.edu/baseball/index.html for additional interesting science-based information on the game of baseball.

References

Baseball highlights: http://memory.loc.gov/ammem/jrhtml/jr1947.html

Jacobs, Steve. Whelmer #22: Energy Transfer. Whelmers – McREL’s Accessible Science Series, Mid-continent Research for Education and Learning. Accessed October 4, 2004. [Golf ball/ping pong ball energy transfer demo] http://www.mcrel.org/whelmers/whelm22.asp

Momentum: http://www.physicsclassroom.com/Class/momentum/index.cfm

Momentum and energy loss of balls colliding against different surfaces: http://www.iit.edu/~smile/ph8709.html.

The Exploratorium http://www.exploratorium.edu

Other Related Information

Browse the NGSS Engineering-aligned Physics Curriculum hub for additional Physics and Physical Science curriculum featuring Engineering.

Copyright

© 2004 by Regents of the University of Colorado.

Contributors

Bailey Jones; Matt Lundberg; Chris Yakacki; Malinda Schaefer Zarske; Denise Carlson

Supporting Program

Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder

Acknowledgements

The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.

Last modified: August 5, 2021

How Does height affect the bounce of a ball? – Mvorganizing.org

How Does height affect the bounce of a ball?

Thus a typical ball bounces to 60% of its original height because it stores and returns 60% of the energy it had before the bounce. When you drop a ball from a greater height, it has more kinetic energy just before it hits the floor and stores more energy during the bounce—it dents farther as it comes to a stop.

What is the relationship between drop height and bounce height?

The relationship between drop height and bounce height is only linear for small drop heights. Once a ball reaches a certain height, the bounce height will begin to level off because the ball will reach its terminal velocity.

How does a bouncing ball lose energy?

When a ball hits a wall or surface, it makes a noise, which is a loss of energy from the ball’s bounce. It also will generate some amount of heat, another loss of energy. Friction from the wall will cause energy loss as well as air resistance while the ball travels.

What causes a ball to bounce higher?

The faster an object moves, the higher its kinetic energy. A lot of it goes back into the ball, giving it more force to pop back up into the air—so the higher the potential energy, the higher the kinetic energy, and the higher the kinetic energy, the higher the bounce!

Why was it important to drop the ball from the same height three times?

Answer: It is important to do this to test your theory multiple times, so that you can see what effect the drop has on it when doing this multiple times. The numbers were slightly different because the recordings will not always be the same.

What surface does a ball bounce best on?

As the ball is released, gravity pulls the ball downwards and transforms that potential energy into kinetic energy, the energy of motion. The harder the court surface is the more energy a dropped ball retains and the higher it rebounds. A basketball bounces pretty well on hardwood, but even better on concrete.

Why does a ball bounce less on carpet?

When a basketball bounces off of a surface, some of its energy is absorbed by that surface. A hard surface, such as concrete, absorbs less energy compared with a soft surface, such as a carpeted floor. The more energy absorbed by the surface, the less that remains in the ball for it to bounce.

Do heavier balls bounce higher?

Both balls will fall at a similar speed, but because kinetic energy is proportional to the mass of the object, the heavy ball reaches Earth with more energy. It will not necessarily rebound higher, as it also needs more kinetic energy to reach a specific height again.

How do you measure the bounce height of a ball?

Paint each of the balls with poster paint in a circle around the ball so that you can hold the ball on both sides to bounce it. Stand 1 meter from the wall. Measure this distance using a meterstick. Bounce each ball toward the wall without using any of your own force.

How do you calculate average bounce height?

MATERIALS: Tennis ball, meter stick. Step 1: Drop the ball from 100 cm. Measure how high it rebounds after the first bounce. Repeat three times, then find the average height after one bounce.

How does the temperature of a tennis ball affect the height of its bounce?

When the temperature increases, the gas molecules inside the tennis ball expand. As the molecules expand, their energy increases as they bounce around more erratically. This increased energy and movement results in a higher bounce. As a result, a cold ball has a much lower bounce.

How do you measure rebound height?

Just using these two measurements, I can find the rebound ratio. Using the geometric sequence formula, we have 111=200(r)(2−1). 200 represents the initial height, and (2, 111) represents the second height after the first bounce at 111 cm. We now know that this ball has a 55.5% rebound ratio.

What is the effect of drop height on the rebound height of a ball?

If the drop height increases, then the resulting bounce height will also increase, because as the drop height increases, so does the gravitational potential energy which can be converted back into kinetic energy on the rebound.

What is the rebound height?

The Synthetic Turf Council (STC) and FIFA recommend that a soccer ball rebounds to a height between 60 to 100 centimeters on a community field, and 60 to 85 centimeters on a stadium field. These ranges are based on a comprehensive study done on natural turf fields.

How many times will a ball bounce before coming to rest?

The series of heights is infinite, so before stopping, the ball must bounce an infinite number of times. #1.

Why does a ball bounce lower each time?

Since the height to which the ball will bounce is directly proportional to its energy (barring effects of air friction), with a coefficient of restitution of less than one the ball will bounce less and less high.

How many times can a ball bounce?

In an idealized situation with a fixed coefficient of restitution between 0 and 1, a ball bounces an infinite number of times in a finite amount of time and travels a finite abount of total distance, with the frequency of bounces approaching infinity as the time approaches the limit of time based on the initial …

What affects the bounce of a ball?

The combination of the material properties of a ball (surface textures, actual materials, amount of air, hardness/ softness, and so on) affects the height of its bounce.

When a basketball bounces against the ground and gets deformed and then recovers its shape?

When a basketball bounces against the ground and gets deformed and then recovers its shape, the air inside that ball is temporarily compressed and will again have its original volume when the ball recovers during the rebound.

Does temperature affect bounce height?

One factor that can influence the bounce of a ball is the temperature of the ball. A warmer ball will bounce higher than a cold one. The reason for this is twofold. In a hollow ball, the change in temperature causes a change in air pressure within the ball.

How does temperature affect the restitution of a bouncing ball?

The temperature of the ball influences its coefficient of restitution. A warmer ball will bounce higher than a cold one.

Does the size of a basketball affect how high it bounces?

The size of the ball can affect its bounce due to air resistance, surface volume and density. However, mass can also play a part in how a ball bounces. If two balls contain the same mass, but are of different sizes, the larger ball will bounce less due to greater air friction against its surface.

Does density affect bounce height?

Density does affect the bounce height (to some extent), in particular, due to air drag: the higher the density, the less significant is the effect of air drag.

Does the amount of air in a basketball affect the shot?

The air pressure in a basketball can’t affect how you play and how good your shot is. Ones shot can defer at anytime and it really doesn’t depend on the air pressure in the ball. We can’t prove this because we miss shots even when the balls is perfectly inflated.

What is the best air pressure for a basketball?

8.5 pounds per square inch

How high should an NBA ball bounce when dropped?

about 1.80 m

Why does my basketball keep losing air?

Basketballs tend to lose a little air when left unused and through normal use over time. In order to bounce properly, basketballs need the right amount of air pressure. To get the most out of your basketball it is very important to keep it at its recommended air pressure, and to inflate and deflate it correctly.

Can you pop a basketball?

Basketballs don’t really pop, actually. Not usually. One of my shots once took a funny bounce off my driveway hoop, a car ran over the ball and it popped extraordinarily loudly. Like a gunshot, almost.

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Bounce Ball | bounce juggling

Bounce Jugglng Ball 64 mm

The 64mm Play Juggling bounce ball is mid-rang size of the standard sized of juggling balls. The size is good for holding 3 in one hand, and you can very easily hold 4 in one hand if you are around 6 feet tall. It would be good size for ball bouncing between 3-7 balls. The seam between the halfs of the ball is very slight. These bounce balls are an excellent value, coming in several bright colors and having a 90% bounce ratio, and much cheaper than a pure silicone ball. These g-force balls are great to get started to learning bounce juggling patterns. They feel great in your hands, clean up great with soap/water, and come in a nice selection of colors.

The G-force bounce ball is a compression molded rubber ball, which comes in four sizes, 50mm, 60mm, 64mm and 70mm. This was the first bounce ball that had comparable quality to a silicone ball, which used to be the most common bounce ball. The colors are bright and there is no significant seam line or fill hole on the ball.

They have a very similar bounce to a silicone ball, slightly higher. The balls have matched weights except for white ( which has much heavier pigment) so when ordering do not mix white with other colors. For example a white 70mm ball has a weight of 205 grams, whereas a 70mm colored ball is 190 grams.

• G-Force bounce ball 50mm size, 1.96 inch (a golf ball is 42mm) and has a weight of 75 grams. The ball was made for number bounce ball passing. Usually for 9 or more ball passing. It could also be a good bounce ball for small children under 4 feet tall. Because of it odd small size and use as a numbers passing ball it only is made in white.
• G-Force bounce ball 60mm size, 2.36 inch (a racquetball is 57mm) and has a weight of 121 grams. This size ball can also be used from numbers passing, but it is possible depending on your hand size to hold four in one hand. Most commonly this ball is a good size for smaller adults and children. The 60mm size is also good for using for numbers juggling, bouncing more than five ball.
• G-Force bounce ball 64mm size, 2.51 inch (a tennis ball is 65mm) and has a weight of 164 grams. This is the most popular size bounce ball. This ball is good for both advanced and beginner bounce jugglers. With a weight of 164 grams it still light enough for using as a combination ball, combining both air juggling and bounce juggling.
• G-Force bounce ball 70mm size, 2.75 inch (a hard baseball is 73mm) and has a weight of 190 grams. This is the largest size ball we sell, and at 190 grams it is really to heavy for air juggling for most jugglers and is better suited for just bounce juggling. However ball could also be used for air juggling if you where at least 6 feet tall and/or used to juggling very heavy juggling balls.

To help you select the correct size of juggling balls, look at our Juggling Guide and Tips section listed in the bottom footer of the home page.

/juggling-guides-tips/how-to-select-a-juggling-ball-size/

diameter 2.5 inch (64 mm)
weight 5.8 ounce (164 grams)
made of compressed rubber
molded in Italy

by Keon E. on 07/24/19

Great product. The rubber smell wears of with use.
I bought 3 yellow, 3 orange. They have a LOT of spring. Great price!!!

by spencer D. on 12/25/19

by Shawn K. on 01/10/20

These are great bounce balls for the price. I purchased the 64 which feel like a great size and weight for me for numbers juggling. Be careful because they are easy to nick if the bounce into anything with an edge.

by Jonathan Root on 05/12/20

These are great bounce balls, very responsive, and way less expensive than silicones and the 64mm are plenty big for everything, even if you want to use them on stage.

by Dominic C. on 12/25/20

I’ve never used bounce balls until now, however they feel really nice and they bounce where I want them to go, and they are really consistent even with multiple bounces.

by Keith N. on 01/18/21

The rainy weather of the pacific northwest combined with the low ceiling in my basement apartment led me to get into bounce juggling. I’d done minor 3 ball bounce stuff before with lacrosse balls, but not much. I picked up 7 of these and LOVE them. Size and weight seems great; I can still mix in a bit of toss juggling into the patterns. And the bounce from them is phenomenal. At about ⅓ the price of silicones! Sure, I’ve heard silicones will last longer. But given these are my first set and I’m not doing shows, they’re perfect for what I need. The only thing I would mention is, you’ll want to childproof your room that you’re going to be practicing in. Like someone else mentioned, if one hits a sharp corners, it will get knicked/cut.

by C. Drown on 04/17/21

Great feel and a great bounce back.

by J. Maisonet on 05/27/21

The bouncing balls are excellent, the service amazing and the shipping really fast!
Thanks! ?

The Difference Between a Slam, Wall and Medicine Ball

Sometimes a dumbbell or kettlebell just won’t work for an exercise. Imagine doing a chest pass where you throw a free weight to your partner. These can be too awkward to grip or use for some exercises. Instead, put a spin on your routine with a workout ball. But which one should you choose?

Slam balls, wall balls and medicine balls are slightly different from one another. Each can serve certain training purposes within a workout. So, when should you go for a slam ball versus a medicine ball or even a wall ball?

Using this breakdown, you can better identify the right equipment for your routine.

THE SIMILARITIES

Before you begin, it’s important to know the fundamental characteristics of weighted balls. This can help you better understand when to use each one over other equipment options.

• Slam, wall and medicine balls can vary by weight and size. Smaller ones can be a little larger than a softball. Larger options can roughly be the size of an inflatable beach ball. The balls can vary in weight from two to 50 pounds but commonly weigh between five and 20 pounds.
• Workout balls are available in different textured surfaces to help improve grip.
• Weighted balls can also be a great addition to partner workouts.

THE DIFFERENCES

It’s important that you can differentiate the three workout ball styles. You don’t want to damage your equipment while doing exercises that aren’t suited for it.

WHAT IS A SLAM BALL?

The design of a slam ball allows it to be used for throwing exercises. The no-bounce, heavy-duty rubber shell gives it durability that softens the impact. This is so the ball won’t bounce back or break when thrown. Slam balls are versatile and can be used for most medicine ball exercises. The slam ball encourages you to use your full body as you throw. This can help improve core strength and explosiveness.

The durability makes a slam ball great for exercises, such as:

• Overhead slams
• Broad jump to passes
• Lateral throws
• Chest passes
• Squat throws

WHAT IS A WALL BALL?

Wall balls are also used in throwing exercises but should only be thrown at a wall. Walls balls feature a durable shell that can help maintain its shape. The wall ball is typically the largest of the three weighted balls.

Wall balls are for exercises directed toward a sturdy wall, such as:

• Side throws
• Crunch throws
• Overhead wall ball tosses

WHAT IS A MEDICINE BALL?

Normally, medicine balls come in a larger variety of designs. These workout accessories are commonly abbreviated to “med balls” or “MBs.” Many med balls are made of leather, rubber, vinyl or plastic. You can also find some options featuring handles to help you with easier gripping. Unlike slam balls, med balls should not be thrown to the ground. They can potentially bounce back or break. Also, they can sometimes have a softer shell.

Some popular medicine ball exercises are:

• Rolling push-ups
• V-ups
• Med ball planks

When classic dumbbells aren’t doing the trick, consider using a weighted ball.

Now that you’re more well-rounded on free weights, you can pick out which type of workout ball is best suited for you and your exercises.

Why Does A Rubber Ball Bounce Back While An Iron Ball Doesn’t? » Science ABC

Whether entertaining yourself on a rainy afternoon by bouncing a ball off the wall or watching an exciting game of baseball, we’ve all been entertained in countless ways by this banal spherical toy. The most enjoyable of all, however, may be bouncing a rubber ball with a lot of force and watching it careen in all directions. Unfortunately, you can’t have nearly as much fun with a plastic or metal ball.

That begs the question, of course, what makes a rubber ball so special? Why are rubber balls the ultimate bouncing toys? There are two factors that contribute to bounciness; one is the elasticity of the material out of which the ball is made and the other is related to the interaction between the force at which it is bounced and that elasticity.

What Makes Rubber Elastic?

Elasticity refers to the readiness/quickness with which a material returns to its original shape after being compressed or stretched. Rubber is made of long tangled strings of carbon attached at different points along its length to other strings of carbon. As such, rubber has very strong molecular bonds. The long molecular chains of rubber can physically rotate around the chemical bonds that hold them together, which results in the property of flexibility. This helps rubber to momentarily deform its shape without breaking. Since the molecular chains are cross-linked, rubber can rapidly return to its original shape after deformation.

source: “RubberSyn&Natural” by Smokefoot – Own work. Licensed under CC BY-SA 3.0 via Commons https://commons.wikimedia.org/wiki/File:RubberSyn%26Natural.png#/media/File:RubberSyn%26Natural.png

The Physics of Falling

Whenever an object is lifted off the ground and raised to a certain height, work is done against the weight of the object, which is stored as potential gravitational energy. When the object – in this case a rubber ball – is released and falls to the ground, the force of gravity acting on the ball causes it to accelerate, converting potential energy into kinetic energy. Just before the ball collides with the surface, all the potential energy is converted into kinetic energy.

At the molecular level, when the ball comes in contact with the surface of the ground or wall, the molecular strands of the ball are compressed or squashed by the downward force acting on it, coupled with the upward force exerted by the ground. The ball changes shape from a circle to an oval.  As the ball changes shape, the force produced by the bonds, which hold the different strands of rubber together, becomes larger.

Changes After Impact

Upon impact, the ball comes to an abrupt halt, but still possesses a great amount of kinetic energy. Some amount of energy that the ball contains is absorbed by the surface, but the remaining has to go somewhere, so it is stored as elastic energy. Again at the molecular level, the downward force on the strands decreases, while the force exerted by the bonds increases, which results in the strands regaining their original shape. It takes a very short time for the ball to come to a complete stop, after which the elastic energy of the ball is released and the ball enacts a force on the ground. There is an equal and opposite force on the ball in the upward direction (Newton’s Third Law), which makes it bounce. The conversion of elastic energy to kinetic makes it rise against the ground. In other words, it bounces back into the air!

In case of a plastic or metal ball, the material is not elastic, although it has the same amount of kinetic energy. The surface that the ball strikes will absorb most of the energy upon impact and since the material is non-elastic, it will not be compressed or reshaped, which would give it the required amount of force to rise (bounce). Also, the transfer of kinetic energy to the surface the wall will lead to a dent or a hole in the wall, since the force has nowhere else to go!

Related Articles

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The surface also matters. If the same rubber ball is bounced off a carpet, it won’t rise or bounce to the same height as when bounced on solid ground. The time it takes for the ball to come to rest is longer, due to the compressibility of carpet, which means that more force is transferred to the carpet, thus leaving less force for the “bounce back”.

Now that you know the science of elasticity, try bouncing a few things off your walls and see what happens!

Tennis balls: structure, types and characteristics

The tennis ball is one of the key components of tennis equipment. Neither game nor training can take place without it. Just like rackets, tennis balls affect the quality of the game. Did you know that there are 5 different types of tennis balls? The answer to this question can be found in our review. In addition, we will tell you about the structure of the ball and what characteristics it should have.

Types of tennis balls

Tennis balls have different playing characteristics depending on the peculiarities of manufacturing. The most important feature is core filling. It matters a lot whether you are playing a ball whose core is filled with air or gas. Core pressure and thickness also play a big role.

Tennis balls can be divided into two categories: pressure balls and non-pressure balls. Another category of balls is balls for children.

1. Pressure balls. Balls of this type are filled with gas (eg nitrogen). The gas provides high pressure inside the rubber core. This increases the bounce height of the tennis ball. These balls are used in professional and amateur competitions. The downside of such a ball is its fragility. Since pressure balls have a small core thickness, the gas escapes over time. This results in a loss of pressure, which noticeably reduces the ball’s rebound. For this reason, pressure balls are always sold in sealed containers.This can be recognized by the hiss that is emitted when opening the package.
2. Tennis balls without pressure. These balls are filled with air. In this case, the two rubber hemispheres are glued together under normal air pressure. Another difference from a ball with pressure is the thickness of the walls of the core. Balls without pressure are much thicker. The material composition of the rubber core also varies. This is due to the fact that in balls without pressure, only the core affects the dynamics of the ball when bouncing. Therefore, elastic materials are used to make the core.The biggest advantage of non-pressure balls is their long service life. They are filled with normal air, and it is not in danger of leakage. However, the thick walls of the core make the ball feel slightly heavier than the ball with pressure when it strikes. In addition, the unpressurized ball moves slightly slower and has a lower bounce. For beginners and amateur tennis players, it is recommended to use non-pressure balls. They are distinguished by their low cost, durability and, above all, are ideal for training.
3. Tennis balls for children. There are special tennis balls for children. They are designed for training and have low blood pressure. They are soft and pleasant to the touch. In addition, children’s tennis balls are slower, which gives children more time to react to the impact. Children’s balls are usually two-colored.

Tennis balls: building

A tennis ball consists of two components: a core and a felt cover.The ball’s core is made up of two hemispheres that are glued together. Inside, the core is hollow and consists of a rubber-like mixture of various materials. The core affects the basic playing characteristics of a tennis ball, especially weight and rebound. Depending on the type of ball, the core is filled with either a special gas or regular air. Outside, the ball core is covered with a protective felt layer. It is durable and provides durability to the ball. It also improves ball spin. The bright green color of the ball provides better visibility on the court (in the past, tennis balls were white).

Tennis Balls:

Standards

1. Dia. The diameter of the ball should be between 6.54 and 6.86 cm (2.57-2.70 inches). Although the error range is quite small, diameter is still a significant factor in ball acceleration. As a rule, balls with a smaller diameter have a higher speed due to less air resistance during flight.
2. Mass. The ball must be at least 56.0 g (1.98 oz) and no more than 59.4 g (2.10 oz). Differences in mass also affect the acceleration and rebound of the ball.For example, the rebound of a heavier ball is slightly lower.
3. Rebound height. The bounce height of the ball must be between 135 cm and 147 cm (53 – 58 inches). The height of the rebound, as already mentioned, is strongly influenced by the thickness of the walls of the nucleus.

Author of the publication: Evgeniya Gerasimova

I live in the city of Moscow. Graduated from Moscow State University with a degree in Journalism.I have been working in the field of sports analytics for over 3 years.

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90,000 BALL IN PLAY | Miscellaneous | Category list | Blog

Football, in the form in which everyone is used to it, has been around for 150 years. Over time, the visual component has changed, for example, the appearance of the participants, the game itself has become more technologically advanced, but the most tangible changes have happened with the soccer ball.The new official soccer ball is presented to athletes and spectators before each World Cup. This sports equipment is becoming the most recognizable item in the football industry for the next 4 years. The focus is on new design, new technologies and, as a result, new characteristics: rebound, flight and speed.

Until the 60s of the last century, athletes played football with a leather ball with a nipple hidden behind a lacing. Playing with such a ball in wet weather became hazardous to health – the ball got wet, became heavy and the injuries received by such a projectile were a common playing practice.

In 1930, the hosts of the tournament and the Argentine team met in the World Cup final in Uruguay. It is noteworthy in this game that the first half was played by the Argentinean ball, with a score of 2: 1 in favor of Argentina, and the second half by the ball of the Uruguayan national team, which surpassed in size and weight. The match ended 4: 2 in favor of Uruguay.

Before soccer ball makers began experimenting with designs and colors, the soccer ball underwent major changes twice.

The old-man brown lace-up ball (T-Model) was used from the first World Cup in 1930 in Uruguay until 1966 in England.Over the years, the color, weight and number of stitched panels have changed slightly.

The next evolution of the ball was the 1968 Telstar from Adidas, created for the 1970 Mexico World Cup. It is no coincidence that the first Telstar received such a name. In the late 60s, television had already come to every home, but the screens were black and white, and the solid brown balls, which were then common, were lost against the background of the field.

Telstar, developed by Adidas, aims to remedy this situation, to give TV fans the ease of watching the gameplay.To do this, its 12 pentagonal and 20 hexagonal sections were painted in a checkerboard pattern, in black and white. Telstar became a “tele-star”. Another legend says that Telstar is named after the first communications satellite launched into orbit. The black and white checkered ball was used in two tournaments in a row.

From 1978 to 1998, during the matches of the World Cup, black and white balls flew into the gates, but already with triangular elements – triads. The first such ball, called the Tango, consisted of 32 pentagonal panels and was decorated with black triads.The triads created the illusion that the ball was made up of 12 white circles.

The balls were subsequently very similar, with the exception of balls in Mexico (1986), Italy (1990) and the USA (1994) with original outlines and images.

The characteristics, first adopted in 1954 by FIFA official ball standards, which set the size, weight and diameter, remain unchanged. Today the current requirements of the International Football Federation are as follows:
Ball circumference – 68-70 cm
Weight at the start of the match – 410-450 g
Pressure – 0.6-1 atm.

In 1982, at the championship in Spain, they played for the first time with a ball made of genuine leather and synthetic materials – Tango España.

The hero of the next tournament in Mexico – the Azteca ball is entirely made of synthetics. Then the age of genuine leather soccer balls ended.

The creators of sports equipment endow their products with incredible lightness and aerodynamics, qualities that make shots on target spectacular and dangerous for the goalkeeper.

In 2014, at the World Cup in Brazil, the technology of automatic detection of a goal was applied – a special chip is sewn into the ball, which helps to accurately determine the crossing of the goal line and sends a signal to the head referee of the match.

The most memorable balls

There are 21 official World Cup balls, including the 2018 ball.
But several of them will forever go down in the history of football due to their unusual properties or incredible game events associated with them.

The first of these is Azteca. He was filmed in the famous football photo in which Diego Armando Maradona hovered in a jump. This is the very moment in front of the famous Hand of God, when Maradona sent the ball into the goal not with his head but with his hand, and the referee made a mistake and counted the goal.

The Fevernova ball, which was played at the World Championships in Japan and South Korea in 2002, perfectly round in appearance, was remembered for the fact that it finally lost its dark spots.

The 2010 South African Jabulani ball, along with new technology, changed the game itself.
8 panels bonded with thermal bonding technology made the flight and bounce of the ball less predictable, and shots of unrealistic force and speed became available to all players. This ball, as it were, wags during the flight, disorienting the goalkeeper.

Our ball

On November 9, 2017, the official ball of the World Cup in Russia was presented at the Artplay design center in Moscow. The new ball was named Telstar 18, a name it inherited from the legendary 1968 Telstar soccer ball that was played at the 1970 World Cup.

Telstar 18 is created using seamless technology – six panels, obviously irregular in shape, are thermally bonded. As conceived by the manufacturer, this helps to better control the projectile and reduces moisture absorption. The ball has a molded latex chamber and cannot be deflated. Size – 5 and weight – 420-455 g, meet FIFA requirements.

Another feature of the ball is its color. Pixel black-and-gray gradients on a white background are a hereditary trait of the ’68 ball and at the same time a reference to the evolution of television: the picture has long changed to color and clear, but even it is sometimes subject to distortion during broadcast.

Textured ball surface with good grip on athletes’ boots.
NFC chip embedded in each official ball makes it interactive and by connecting with it using a smartphone, you can learn more about the ball and special events for fans of the 2018 World Cup. color scheme: the stripes of the ball have become black-red-gray.

The defenders’ goals helped Fakel Voronezh beat Kaluga.Latest news from Voronezh and region

Joint project

The Voronezh club strengthened its leadership in the Center zone, having won a confident 2: 0 victory over FC Kaluga in the 12th round of the championship in the Center zone of the second division. Both goals in the Voronezh team were scored by defenders – Viktor Stroyev and Yuri Dubrovin.

The match took place on an artificial turf, which is unusual for Voronezh residents. According to the head of the public relations department of FC Fakel Sergei Postnikov, after the pre-game session on Wednesday evening, the team’s coaches called the pitch “heavy” and noted the quick rebound of the ball.However, the blue-and-white mentor Vladimir Mukhanov once again showed conservatism and did not change the lineup, which brought the club major victories in the home match against Avangard Kursk and away with Zenit Penza. Kaluga residents were also not going to sit out in defense, despite the eight-point gap from the leader of the Center zone. Already in the first minute, the blue-and-white missed a sharp attack by the home team. Having played the third round of the 11/12 season at Fakel, forward Dmitry Vakulich tried to throw goalkeeper Alexander Sautin, but the ball never hit the goal.By the way, for the Voronezh goalkeeper, the game against Kaluga was the fifth in the current championship. According to this indicator, Sautin caught up with the young goalkeeper Dmitry Ternovsky, who in the last rounds dropped out of the cage of players who were in the application for the match.

However, by the end of the first ten minutes of the meeting, Fakel had already taken the lead. Defender Viktor Stroyev distinguished himself by scoring a goal with a powerful long-range shot to the top corner of the goal. This is the second goal in a seven-year professional football player’s career. Similarly, Stroyev, then playing in Tomsk, distinguished himself in the Rostov-Tom match in November 2011.On the 28th minute of the game against Kaluga, the Fakel’s left-back tried to hit the goal again, but this time goalkeeper Andrey Lunev had no difficulty in catching the ball. Kaluga gradually recovered from the initial success of the Voronezh team and leveled the game. Goal Sautin the home team threatened mainly from free throws. But even Fakel rarely managed to create sharpness in the opponent’s half of the field. In such a tough struggle in the center of the field, Fakel captain Dmitry Michkov was unlucky, who was injured at the end of the first half.The most experienced defensive midfielder himself asked for a replacement – instead of him, the coaches released the nominal defender Vladislav Khatazhenkov. And at the last minute left midfielder Konstantin Skrylnikov got a chance to excel. He joined the attack, which began on the right flank, Anatoly Nezhelev, received the ball in the penalty area, standing with his back to the goal. The hosts’ defender did not let the blue-and-white midfielder turn around, and Skrylnikov fell to the lawn. Arbiter Alexey Pchelintsev saw no reason to stop the game in this episode, and a minute later blew the whistle for a break.

In the second half of the match, the nature of the game did not change: the guests continued their attempts to break through to the goal of Kaluga residents mainly due to the activity of the flank players, who were supported in the center of the field by Albert Sharipov, the hosts tried to knock down the attacking impulse of Fakel by aggressive play in tackles and counterattacks. So that the pressure on the opponents does not weaken, Vladimir Mukhanov released Dmitry Sokolov and Alexander Antipenko onto the field, replacing Konstantin Skrylnikov and Kirill Pogrebnyak, respectively.And on the 68th minute the next standard of the Voronezh team ended with a goal. Anatoly Nezhelev filed from the right flank, Kaluga’s defenders took the ball out of the penalty area, but the guests got it again, and Yuri Dubrovin shot straight into the bottom corner from Lunev’s penalty area.

Kaluga residents reiterated their desire to narrow the score gap with the help of standards, but their attempts lacked precision and organization. Arsen Oganesyan, who replaced Dmitry Vakulich, managed to organize almost the most acute moment in the second half, but his breakthrough on the right flank ended with Sautin taking the ball without much difficulty.Despite the fact that the referee added 4 minutes to the main time of the match, the Voronezh team brought the game to victory without any particular difficulties. She became the fifth in a row for the team.

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Hard start | FC Lokomotiv

The teams approached the first match of the Europa League in different physical and emotional states. By the end of August, Lokomotiv played four rounds in the Premier League, while the Cypriots have not yet played official matches this season.

The best “rolling in” of the “railroad workers” in the season was evident already at the beginning of the match. The guests quite calmly restrained the starting onslaught of Apollo, which rushed forward in front of the native audience, and by the third minute they easily pushed the game to someone else’s half of the field. One of the main characters in the attack was Umar Niass , who made his debut in the starting lineup of Loko in the game in Cyprus. In one of the episodes, the Senegalese masterfully took the ball launched forward by Vedran Chorluka , quickly turned around and shot straight into the near corner: the ball hit the outside of the net.

Another, slightly more serious attack was soon launched by Alan Kasaev and Dmitry Tarasov . The first escaped from the Cypriots through the center and with a hidden pass brought the second to the goal, whose powerful blow fell wide of the target.

By the thirtieth minute of the meeting, Loko almost realized two sets in a row. Submission Manu Fernandes from the corner went into the midst of the players, Bruno Vale knocked the ball out of the penalty area, and Alexander Samedov was the first to finish.Number 19 hit the bottom aimingly, but the ball eventually got entangled in the defenders’ legs. The next free kick, won by Kasaev, was taken by Samedov himself: after his canopy, the ball darted around the penalty area and ended up in the goalkeeper’s hands, never reaching the far post, on which Niass was guarding the rebound.

Nevertheless, the “railroad workers” went to the break with an advantage of one goal scored. Shortly before the end of the half, Kasayev, one of the most active in the first 45 minutes, playfully scattered a couple of defenders with feints, moved to the center from his left edge and sent the ball from outside the penalty area exactly to the far corner!

The second half began with a substitution: Dame N’Doye replaced Niass.Apollo responded with a dangerous attack: a serve from the left flank passed into the penalty area Guilherme , and Meryem almost closed it on the far post.

At Loko, Kasaev continued to conduct in many respects in creation. In one of the episodes, Alan fell into the penalty area on the right and with an accurate pass brought Vitaly Denisov to an empty far corner: in an ideal situation for a goal, the left-back sent the ball past.

The next couple of minutes almost became a terrible repetition of the episode in Kazan for all Lokomotiv fans.Papulis bumped into Tarasov’s leg half a meter from the line of the penalty area, the referee pointed to the “point”, but after consulting the linesman, he changed the decision and justly “punished” the guests only with a free kick, which the defense easily coped with.

Trying to seize the initiative from the Limassol players who have revived in the second half, Lokomotiv itself went on the attack, but N’Doye scored only a couple of offside positions in ten minutes.

And 15 minutes before the end, the “railroad workers” found themselves in a difficult situation. Yan Tigorev in a harmless situation in the center of the field stepped on the opponent’s Achilles and was sent by the referee to the locker room with a straight red card.

Most of the Cypriots realized in an exemplary way: Abraham, after a quick counterattack, fell out on the goal and outplayed Guilherme.

A couple of minutes before the end of the match, Loko turned out to be nine at all: Denisov was sent off for the second yellow card. The hosts, driven by the stands, immediately staged the final assault, which did not subside until the final whistle, and already in stoppage time were close to a goal scored, however, after a free kick, Tyuram shot into the post, and one of his partners was not accurate on finishing.

Lokomotiv’s start in the Europa League turned out to be difficult, but the away goal gives hope for a favorable outcome of the confrontation with Apollo.

Apollo – Lokomotiv 1: 1 (0: 1)

Goals: Kasaev, 39 (0: 1). Abraham, 80 (1: 1).

Apollo: Bruno Vale, Merkis, Robert, Stilianu (Mulder, 70), João Paulo, Vasiliu (Thuram, 79), Gulion, Meriem (Rezek, 69), Amdani, Abraham, Papulis.

Lokomotiv: Guilherme, Shishkin, Chorluka, Dyuritsa, Denisov, Tigorev, Tarasov (Mikhalik, 65), Samedov, Fernandesh, Kasaev (Maikon, 62), Niass (N’Doye, 46).

Warnings: Stilianu, 32. Merkis, 53. Denisov, 63. Micon, 88.

Deletions: Tigorev, 75 (rough play). Denisov, 87 (second housing estate).

Chief Referee: Ivan Bebek (Croatia).

August 21. Nicosia. GSP Stadium.

Dariya Konurbaeva, press service of FC Lokomotiv

Why are the material, weight and size of a soccer ball important?

Football is a popular game with a mass of fans and supporters all over the world.To realize the desire to become a football player, amateurs and professionals acquire a soccer ball. Many people like to play football, of any age, gender, social background or nationality. After all, this game brings together, unites and gives a huge amount of emotions.

This is an important attribute of the game of football, familiar from childhood. It cannot be confused with any other sport. However, even an avid football fan does not know the answer to the question about the main parameters of this sports equipment: the size of a soccer ball is an important factor in its choice.For purposes, balls of a certain size are purchased. The weight of the soccer ball is also important. The soccer ball is chosen according to the type of surface on the playing field – grass, soft or hard artificial turf, gravel, asphalt, sand or the floor in the gym. There are other requirements for a soccer ball. The ideal ball is spherical, elastic, and has the appropriate size and weight.

A Journey Through History

In the early days of the game, an animal’s bladder was used to make a soccer ball.However, it could not be used for a long time, because due to the strikes on it, such a first soccer ball became unusable. Ball manufacturing technology has undergone significant changes since the discovery of vulcanized rubber in 1838. Years later, in 1855, American inventor Charles Goodyear introduced the first rubber ball. It differed from its outdated counterparts in rebound and durability.

Photo 1. The soccer ball consists of black and white pentagons and hexagons so that it can be clearly seen on the grass from the stands.

Seven years later, another inventor, Richard Lyndon, created the first rubber ball bladder. Later he managed to develop a pump for the chamber. This invention was recognized at the London exhibition with a special award. After the discovery of rubber and the invention of the rubber tube, it became possible to create a technical condition for the mass production of football balls.

With the founding of the Football Association of England in 1863, a unification of the rules of the game is being created.However, at that time there was no mention of the ball in them. The official standards for the weight and size of a soccer ball (1872). Until that time, the weight of the soccer ball and other parameters were agreed by the parties before the start of the match.

Photo 2. Charles Goodyear invented the first rubber ball.

After the creation of the England Football League in 1888, balls began to be mass-produced, as the demand for them increased. At the beginning of the twentieth century.they became better – the chamber made of durable rubber coped with the pressure. The soccer ball had a tire and an inner tube. Tire material – genuine leather. The cover consisted of 18 panels stitched together. There was a nipple under the lacing.

In the 1960s, a synthetic soccer ball was developed. Natural leather was used in production until the end of the 80s of the twentieth century, after which it was replaced with synthetic materials.

As a rule, the balls were made of leather, which was taken from the rump of cow carcasses, for models simpler used leather from the shoulder blades, cheap and less durable. There were plenty of problems with leather balls. When playing in the rain, the ball swelled, the lacing stuck out, the ball lost its shape. The use of leather for the production of football equipment on a massive scale was costly.

Leader in the production of balls (80%) – Pakistan. And the producers of the city of Sialkot, on the territory of this country, produce 60% of the balls from the world production.Previously, the owners of the plant used child labor in production. At the end of the 2004 European Championship, this topic was raised by journalists. After the intervention of international organizations for the protection of children, the problem was resolved. For the World Cup, which was held in Germany, the balls for the game were presented by the manufacturers of Thailand.

Photo 3. Pakistan is the main country of production of football balls.

Interesting facts from the history of soccer balls:

• matches of the 1970 World Cup, which took place in Mexico, were shown on television.For this, the Telstar soccer ball was developed. It consisted of 32 black and white pieces, as the designers, while developing the product, tried to make the ball visible on the screen;
• The Tango Duralast product, which was made for the 1978 World Cup in Argentina, consisted of 20 pieces: 12 white circles on a black background;
• At the 1982 World Cup in Spain, the leather Tango España soccer ball was used for the last time. The innovation was considered to be rubber, which was applied to the seams in order to reduce water absorption;
• At the World Championships in Mexico, in 1986, they played the Azteca ball, the material of which was made of polymer materials;
• For the Etrusco Unico ball played in the 1990 World Cup, foam was used for one layer;
• Questra – The ball used by the teams at the World Cup in the USA in 1994.In its production, five types of materials were used. The product was subjected to serious testing at that time;
• For the production of the Tricolore product, which was played at the 1998 World Cup in France, synthetic foam was used – it made it possible to give a soft touch to the ball and ensure a rebound at the same time;
• At the 2002 World Championships in Korea-Japan, a Fevernova ball was used with a cut of 32 pieces. In addition, it had 3-millimeter layers (11 pcs.), the microcells of which stored energy during the impact and contributed to stable flight;
• The Teamgeist ball, which consisted of 14 pieces and was used at the 2006 World Cup in Germany, used heat shrink seams. They provided water resistance and compensated for surface imperfections.

Photo 4. The Adidas Telstar professional ball competed in the 1974 FIFA World Cup.

Types of soccer balls

Those who think that the soccer ball is standard and the same for everyone are mistaken.In fact, there is a difference in how it is supposed to be used. Much depends on the place where the game will take place: on grass, lawn or even asphalt. In accordance with this, the following types of soccer balls are distinguished:

1. Professional soccer balls – used for games on all surfaces of soccer fields. In addition, they are used in any weather. When purchasing them, a quality certificate is provided that this projectile has all the qualities and is suitable for professional games.
2. Match balls. Durable among all kinds. Have grip when playing. Used in football competitions.
3. Training balls. They have increased durability, water-repellent coating, thanks to which they are appreciated by fans of yard football, and are widespread.
4. The futsal ball has a low bounce and is smaller in diameter than standard balls.

Professional and match balls are manufactured by manufacturers exclusively for playing on turf surfaces, where matches and football competitions are held.Those who like to play the ball on the asphalt know that manufacturers do not produce special balls for hard surfaces. After all, even the best soccer balls, which are used for playing on asphalt or concrete, wear out and lose their shape.

In addition, soccer balls have a temperature threshold at which they are used for playing. It is -15 degrees. Don’t be surprised when a quality ball falls apart before your eyes after being used to play on asphalt in freezing temperatures.

Photo 5. The futsal ball is characterized by low rebound and light weight.

Ball requirements

cm

9 0318 420-445 g

FIFA Standards Table.

FIFA Approved is a mark that indicates that the ball meets the list of FIFA requirements and confirms its functional and technological characteristics. To get this mark, the ball meets the requirements:

• have a circumference of 68.5-69.5cm. In this case, the diameter is 21.8-22.2 cm;
• clear roundness – when calculating the difference between the larger and smaller diameter values, its difference from the average value does not exceed 1.3%. In this case, the diameter is measured at 16 points, after which the average figure is determined;
• bounce – when the ball is dropped from a 2-meter height, the bounce height is 1.2-1.65 m.An error of no more than 10cm is allowed.
• soccer ball weighs about 420-445g;
• wetting – a test is carried out in which the ball is placed in a tank of water and, rotating it, squeezed about 250 times. The amount of absorbed water increases its weight by no more than 10%;
• soccer ball pressure. During the test, an air pressure of 1 bar is applied to the ball. After 3 days, the ball releases air, the volume of which does not exceed 20%;
• soccer ball shape and size.A special test is carried out in which a ball is thrown at a speed of 35 mph into a steel surface. No seam should be damaged during testing. In this case, the pressure loss, changes in diameter and ball shape should be negligible. The ideal option is the complete absence of such changes.

Balls bearing the FIFA Approved logo are played in official football matches. At all, which are held under the auspices of FIFA or continental associations. Balls to receive the FIFA Approved mark undergo an additional test that simulates 2000 hits on the ball while playing on the field.The correct soccer ball will have unchanging characteristics after being hit 2000 times on a steel plate at a speed of 50 km / h.

Photo 6. Testing the ball to maintain its size and shape under the impact of impacts.

The device of the soccer ball

The layout of the soccer ball, which is used in professional and amateur football, is simple. It consists of an outer surface, a suture, an inner lining of cotton or polyester, and a latex or butyl bladder.

The outer casing of a soccer ball consists of 32 pieces of artificial material or natural leather, of which 20 are hexagons, 12 are pentagons. This design is called a truncated icosahedron: the ball takes on the shape of a ball due to the air pressure inside. This design was presented in 1950 by Select (country of manufacture – Denmark).

An innovation in the production of balls was introduced by Adidas: at the 2006 World Cup, the players played Teamgeist, which consists of pieces of an unusual shape that resemble impellers and propellers.Two years later, at the European Championships, the same company presented the Europass ball, similar to the Teamgeist, but with a different coating, similar to the lemon peel.

Photo 7. Description of the structure of the professional ball Adidas Tango 12

Polyester threads are used as a suture material for a soccer ball. Some balls are sewn by hand, for others a special machine is used. In the manufacture of balls of poor quality, glue is used, which increases their rigidity and, in general, affects its characteristics.Technology such as thermal bonding is used in the production of Roteiro, Teamgeist and Europass balls.

A lot depends on the inner lining of a soccer ball. Thanks to its layers, the shape is leveled, and speed characteristics are improved. Professional balls have at least 4 layers of cotton or polyester, they are combined with each other. In some cases, a special foam is added to improve control and cushioning.

The purpose of the ball chamber is to hold air.The latex chamber retains air worse than the butyl chamber. Foams for futsal balls are designed to withstand the stresses of the hard surface. The valve is lubricated with a special silicon grease – this will help easy needle entry and air retention.

Photo 8. Manual The second seam on the soccer ball is made using a bent needle.

Air leakage occurs due to microspores, the ball needs constant pumping.Latex is pumped up once a week, and a butyl ball once a month. In addition to latex and butyl, polyurethane is used for the manufacture of cameras.

Photo 9. Gala Argentina 2011 – a football equipment with a synthetic surface and a butyl camera.

Design and colors

When choosing a soccer ball, pay attention to the pattern and design features. The product consists of panels on which its aerodynamics and user friendliness depend.The number of panels depends on the intensity of use and other parameters for which the ball model was made.

Among the huge variety of designs for footballs, the 32-panel, which was manufactured by SELECT back in 1962, is considered traditional and popular. A great option for playing on any surface, including stadiums and futsals.

The color of a soccer ball used to be exclusively white or brown. After the advent of televisions, they were replaced by white and black in the form of white hexagonal and black pentagonal pieces.This classic color is commonly used. If for the duration of the match forecasters predict snowfall, then bright colors are chosen, more often orange.

Until 1954 the color of the ball remained brown and only at the World Championships in Switzerland was the yellow ball used. This change was positively met by the fans – the bright color of the shell helped to concentrate on the game.

The drawing applied by the manufacturing companies is patented. They make replica balls, which are made from inexpensive materials, but in their appearance they are similar to professional ones.Designed for practicing techniques by amateur football players.

By a decision made by the Football Federation of FIFA, any advertising and logos are prohibited on balls, at official matches and championships, except for the emblems of the organizers of the competition or competition, the manufacturer of the equipment and signs indicating the compliance of the soccer ball with standards.

Photo 10. 8-panel (top) and 12-panel (bottom) football shells that were used for games at the beginning of the last century.(In the photo on the top right – a footballer of the 30s of the twentieth century)

Features of soccer balls, depending on their size

The size of football balls largely determines the goals and conditions for which they are purchased. Size 1 balls are more often used for advertising purposes and are produced with logos, emblems or advertising slogans. As a rule, the material for their manufacture is synthetics. They have 32 panels, of which 20 are hexagons and 12 are pentagons. The length of their circumferences is no more than 43 cm.In terms of structure, such balls do not differ from other types, if you do not take into account their size.

Balls of the second size are produced for advertising purposes. This is an option for a child under 4 years old. For manufacturing, synthetics, plastic or polyvinyl chloride are used. The circumference in length does not exceed 56 cm, and the mass of a soccer ball of this size is not more than 283.5 g. According to their criteria, these balls are suitable for raising the level of football players, which consists in intensified training and improving the technique of possession of the projectile.The cover of this type of soccer ball consists of 26 or 32 panels. It contains logos, trademarks or advertising slogans.

The third size is a children’s soccer ball, which is produced for training kids, whose age is 8-9 years. Its weight is no more than 340 g, and the circumference is up to 61 cm. In most cases, balls of size No. 3 consist of glued or sewn panels in the amount of 32 pieces. The material of their manufacture is synthetics or polyvinyl chloride. In rare cases, 18- or 26-panel products are produced.

Size 4 balls are intended for playing mini-football or for training sessions for children under 12 years old. FIFA rules state that:

• this ball is in the shape of a sphere;
• material of manufacture – leather or other material;
• the circumference is 62-64 cm;
• weighs 400-440g;
• pressure corresponds to 0.6-0.9 atm.;
• the rebound height from a 2-meter height is in the range of 50-65 cm.

Photo 11.Children’s soccer balls attract with their brightness and cause in the child the desire to play.

Size 5 balls are used in official football tournaments held by FIFA around the world. They are popular and common. The number of balls of this size is higher than the production of other types from 1 to 4 sizes. The circumference of the dango projectile is 68-71 cm, weight – up to 450 g. In addition, there are types of balls that are intended for children’s and women’s football.They differ in size and weight from the generally known parameters of soccer balls.

Photo 12. Women’s football balls are generally lighter in weight.

Materials of manufacture

A leather or rag soccer ball is not used for the game. The variety of synthetic leathers, for such purposes, surpasses natural material in many qualities. By their structure, they are multilayer hybrids, a special role is played by the top layer, which is based on polyurethane, polyvinyl chloride or the materials in which they are contained.

Polyurethane has strength properties. The mass of microbubbles, of which it consists, has a number of valuable physical properties that determine in the technical characteristics: shape constancy (the ability to restore its original appearance after a strike), poise (preservation of the trajectory and angle of movement that the player sets during a strike), flight speed, and rebound. The cost of polyurethane balls is more expensive than those made from PVC.

Comparison chart of soccer ball camera materials.

Polyvinyl chloride (PVC) is considered less practical, but cheaper. This type of synthetic leather is sturdy. When palpated, PVC is similar to plastic in cold weather. Footballs made from this material present some difficulty in handling. PVC is often used to make tires for inexpensive balls.

Compared to polyurethane and PVC balls, the former are softer and have a more natural surface.Most game lovers choose polyurethane products. Under the top layer of polyurethane, some contain a layer of special foam that provides contact with the player’s foot and excellent cushioning. The thicker this layer, the better the contact will be, and the ball will last longer.

Photo 13. Polyurethane material used for the manufacture of soccer balls.

An important part of the soccer ball – “heart”, camera. In its manufacture, as a rule, natural latex or synthetic butyl or polyurethane are used.The main disadvantage of a latex chamber is the gradual release of air. However, in terms of quality, latex products are superior to synthetic ones in elasticity (the camera is stretched to a large size), rebound and memory – indicators that are important during the game.

How to choose a soccer ball for a child?

Knowing the main purchase parameters, the ball search area is narrowed to a minimum. After all, intending to acquire the main attribute for a popular game, many are determined by its weight and size.The ideal option is to purchase a light ball for your child. For those who find it difficult to determine the acceptable size and weight, FIFA offers clear and simple recommendations:

• if the child is under 8 years old, buy for him a soccer ball weighing 312-340 g, the circumference of which is 57-60 cm;
• for the age category of 8-12 years old, balls with a weight of 340-369 g are suitable. Since they belong to size No. 4, their circumference is 62-65 cm;
• adolescent children, starting from 12 years old, are recommended “adult” balls weighing 397-454 g, the circumference of which is 67.5-70 cm.The parameters correspond to a standard size 5 ball.

When choosing a soccer ball for their children, some parents worry that a heavy projectile will hurt their child. But if you can protect yourself from a heavy ball with good football equipment, then a light soccer ball is uncontrollable. The weight must be proportionate to the player.

Photo 14. A separate category of balls – lightweight models for children’s play, which require less effort when kicking.

How to care for the ball?

In order for the ball to last longer, it is important to know the basic rules of its care.This also applies to the soccer ball. If you take care of it, having studied the recommendations of specialists, then you extend its service life. In no case should you sit on your soccer ball and stand on it. You cannot hit the ball hard on the wall, because this will deform it, and as a result, it will swing to the sides during flight.

When choosing a ball, take into account the playing conditions where it will be used. In this case, the main criterion is the weather and the playing surface. If training or games are planned on rocky and rough surfaces, for example, on asphalt, concrete or gravel, then such loads will be detrimental for an ordinary ball.Friction during impacts and jumps on hard and uneven surfaces lead to rapid wear, to cuts in its outer coating. At sub-zero temperatures, you cannot play with a wet ball, since the transformation of water into ice will damage the outer surface and form microcracks.

When cleaning the ball, remove dirt at the end of the game with a damp cloth. In case of contamination, use a mild soap or detergent, which is used for synthetic leather. Do not use harsh cleaning agents.Their concentrated solutions will damage the ball’s seams and outer coating. The ball should not be washed under high pressure water, as moisture seeps into the inner layer. A wet or dirty ball is rinsed with clean water, wiped with a soft brush, wiped off with a dry cloth and left in a dry place where it dries completely naturally at room temperature. Keep the ball away from factors such as cold, heat, high humidity, direct sunlight.

Photo 15.Even the most wear-resistant ball material should be protected from harmful effects, prolonged moisture and low temperatures.

It is important to monitor the correct pressure on the soccer ball. Playing with a pumped ball, as well as an under-pumped ball, is the cause of accelerated surface wear. When inflating, adhere to the pressure recommended by the manufacturers – this is indicated on the surface of the ball. Basically this value corresponds to 0.8-1.0 bar.

Silicone oil is used to extend the life of the soccer ball.Before inflating, drop a few drops of it, which will reduce the wear of the ball by 40-50%. After that, the nipple will become elastic, which is so important in order to prevent damage to the valve and loss of pressure in the ball. Since the nipple, unlike latex or butyl chambers, is less elastic, it is more easily influenced by external factors. These include humidity, uneven surfaces, low or high temperatures. Under the negative influence of these factors, the ball fails.

Every soccer ball loses pressure over time.For some of them, a few days are enough. In a product with butyl chambers, the air pressure is stored longer than with latex ones. To know that the pressure is correct, it is checked more often. Purchase a high-quality pump, spare needles and a special pressure measuring device. Many manufacturers advise on days when the ball is not used for training or for playing, to reduce the air pressure in it. This will help reduce stress at the seams. Thus, the life of the ball is increased.

Today, high quality balls belonging to the middle and high class are produced in two countries: India and Pakistan. There are also low-quality fakes, which are made by a handicraft method: gluing pieces or manual stitching. It is easy to distinguish such fakes from a professional ball. High quality balls are made by craftsmen in factories. One working day makes 1-2 products. These criteria are important, and it is important to pay special attention to them in order not to get into a mess, but to buy a soccer ball of excellent quality.

Video: How the balls of different championships looked since 1930

90,000 BALL. Learn to play table tennis

BALL

The table tennis ball weighs only 2.5 g and is the lightest and smallest ball used in sports games. The balls are made of matte white celluloid or a special grade of plastic. However, there are also rubber balls, which are still played in Japan and even hold individual national championships.

Very often mistakes in the game occur due to poorly matched ball. How do you choose the best ball? When choosing a ball, pay attention to the brightness of the color, weight, correct shape, the same thickness and elasticity of both halves, as well as the seam along which it is glued. The seam should be smooth and run exactly in the middle of the ball. A ball in which one half is thinner than the other is not suitable for play – it has incorrect bounce, uneven rotation and inaccurate flight. A “soft” ball with very thin walls is usually lighter than a “hard” ball and has a weak rebound.A heavy ball rotates less, and because of this, its flight path is not as curved as a light ball.

Learn some practical tips. To check the stiffness of the ball and the elasticity of both halves, take it in your hand and lightly squeeze it with your thumb and forefinger, pressing evenly on the halves. If the force with which you press on the halves is the same and the resistance of the halves of the ball is also the same, then the ball is good. You can check the spherical shape of the ball by twisting it with your palms on a flat surface.If the rotation of the ball is uneven or when viewed from above it appears to be non-circular, then they are undesirable to play.

During the game, the ball breaks from a strong blow or awkward movements, but it can be repaired. If you or your partner accidentally stepped on the ball and there is a dent in it, there are two ways to fix it. The first way. Dip the ball into hot water. The air inside it, expanding from heating, will straighten the dented half of the ball.

The second method requires more care.It is necessary to gently hold the ball with the crumpled part over the fire of a lighted match.

A cracked ball can be repaired as follows. It is necessary to dissolve a piece of celluloid from an old ball in nitro glue and cover the crack with this solution. After the solution has hardened, the place of gluing must be carefully cleaned with fine-grained emery paper.

90,000 Why isn’t the plasticine ball jumping?

The table shows the types of charges that arise in bodies when they are electrified by friction.The names of materials that electrify with mutual friction are located in
…

sharply in different columns.
POSITIVE CHARGES NEGATIVE CHARGES
wool sulfur
You have a charged electrometer at your disposal.
How to determine the sign of its charge using the information given in the table? Choose the correct course of action.
Bring one of the bodies to the electrometer.
If the arrow has deviated to a greater angle, then the electrometer is charged in the same way as the body brought to it.
Rub the bodies together.
Make a conclusion about the charge of the electrometer.Look at the change in the position of the electrometer arrow.
Make a conclusion about what charge each body will acquire as a result of friction.

Today you will learn more about electrifying bodies.
Do you know, for example, what charge the electrometer will receive if you bring a rhinestone to it?
…

friction with flannel? Do not you know? Then read the information below!
12689588.jpg flanel.png
Substances can be arranged in rows in which the previous body is electrified positively, and the next one negatively.Consider the Faraday series!
(+) fur, flannel, ivory, feathers, rhinestone, flint glass, paper fabric, silk, wood, metal, sulfur (-)
Some of the substances in this series were written out in the table, but errors were made. Find them and mark them.
(Be careful! Mark the substances that were entered in the table by mistake!)

Please help me urgently

To solve a problem…….

If the same resistors of 4 ohms are required, do you need to trim the 9 ohms? Draw a similar diagram.

The gas was squeezed, hovering over it to the robot 90 J. At the same time, the gas transferred to the midst of the midst a bit of heat 35 J.
…

energy to gas?

Above the til, the robot was shown 80 J and a bit of heat of 50 J was transferred to the robot. How did the internal energy change?

Today you will learn more about electrifying bodies.
Do you know, for example, what charge the electrometer will receive if you bring a rhinestone to it?
…

friction with flannel? Do not you know? Then read the information below!
12689588.jpg flanel.png
Substances can be arranged in rows in which the previous body is electrified positively, and the next one negatively.
Consider the Faraday series!
(+) fur, flannel, ivory, feathers, rhinestone, flint glass, paper fabric, silk, wood, metal, sulfur (-)
Some of the substances in this series were written out in the table, but errors were made. Find them and mark them.
(Be careful! Mark the substances that were entered in the table by mistake!)
POSITIVE CHARGES
NEGATIVE CHARGES
flint glass
feathers
flannel
silk
sulfur
fur
Ivory
paper tissue
Answer the question!
What charge will the electrometer receive if a flint glass electrified by friction against flannel is brought to it?
Positive.Will not receive a charge.
Negative.

solve the problem 8.25 20 points

solve the problem 8.24 20 points

.