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IELTS READING LEVEL 6.5 – How Soccer Can Help Us Understand Physics

How Soccer Can Help Us Understand Physics

by ReadWorks



Sports provide a great way to understand some concepts in physics. Physics, after all, is the study of matter, motion, force, and energy. And since sports like soccer, swimming and cycling involve bodies moving through space, they can help us understand how the principles of physics work.

Imagine that you’re looking at a soccer ball on a grassy field. If you do nothing to the ball, it will stay motionless on the grass. If you kick the ball, it will roll along the grass before coming to rest again. Pretty simple, right?

For thousands of years, though, people thought that objects like this soccer ball come to rest because they have a natural tendency to stop. It took a famous physicist by the name of Sir Isaac Newton, who lived in the 1600s, to prove that this was not exactly correct.

Newton suggested that objects like the soccer ball have a natural tendency to keep moving. The only reason they stop, he believed, is because an unbalanced force acts on them. By an unbalanced force, Newton meant the force applied to the soccer ball by its environment. When kicked, the surface of the ball travels over the grass, creating friction. The taller the grass, and the rougher the surface of the ball, the more friction is created. And the more friction that exists between the ball and the grass, the less it will travel after being kicked.

Now, imagine that there is no grass. Instead, the ball is resting on a frozen lake. When you kick the ball on the ice, the ball will go much farther than it would have on the grass. This is because ice provides a lot less friction than the grass.

Even so, ice does cause some friction. The ball’s interaction with the frozen water crystals on the surface of the lake eventually causes it to come to rest again. But now imagine that instead of ice, the ball is in a place where there’s no friction at all. The ball is floating in a vacuum. If you remove friction entirely, kicking the soccer ball would cause it to keep going and going at the same speed, until some force caused it to slow down and stop.

To paraphrase Sir Isaac Newton, a soccer ball on the grass will stay where it is unless acted on by a force. Similarly, once you kick the ball, it will remain in motion unless acted on by force. This, in so many words, is known as Newton’s First Law of Motion.

The same principles apply for other sports. Take swimming. Olympic swimmers are in a constant battle with the force of water. Water slows them down. To increase their speed, swimmers often shave their entire bodies, reducing the amount of friction caused by hair. Since a swimming contest can be won or lost by a tenth of a second, anything they can do to remove friction will help-even if it means ridding their bodies of hair.

Recently, Olympic swimmers took to wearing full-body suits in the water, which made swimmers sleeker and reduced underwater friction. Swimmers wearing these suits began to break world records. They started winning all the races. Soon enough, Olympic officials, realizing that these suits posed an unfair advantage, banned the use of suits in Olympic competition. Swimmers had to fall back on their own, hairless skin.

The situation for professional cyclists is slightly different. Unlike the swimmer, who battles the water, the cyclist is confronted with forces from other sources that seek to slow him or her down: the force of the road and the force of the air. Like professional swimmers, pro cyclists are known to shave their body hair, to reduce the amount of friction caused by the wind. But the loss of body hair represents only a tiny reduction in surface friction compared to, say, wearing spandex shorts instead of baggy shorts with pockets that fill up with air as you ride.

To reduce friction and increase speed, cyclists adopt all kinds of techniques. They wear aerodynamic helmets. They crouch low over their bikes. They wear shirts and shorts that cling closely to their skin, preventing air from slipping inside and slowing them down. However, little can be done about the tires’ interaction with the pavement. As in the case of the soccer ball, a bicycle wheel will eventually stop spinning if no force acts upon it to keep it moving. The rougher the road, the sooner that bike wheels will come to a stop.

For this reason, cyclists tend to have large, bulging thigh muscles. These muscles allow the cyclist to continue exerting force on the bicycle pedals, which cause the wheels to keep spinning despite their constant interaction with the road. Of course, other factors come into play, too. The heavier you are, the more work you have to do to keep the bike moving-that is, unless you’re moving down a hill, in which case the gravitational force of your weight acts to your advantage.

Also, your ability to keep your legs pushing the pedals depends on how fit you are, not just how strong your legs are. Many people who are out of shape would run out of breath before they complete a mile-long bike ride, whereas a person who is fit and has a lot of stamina could travel two miles without much difficulty.

Whether you are in shape or not, what really matters when trying to kick a ball, swim a lap, or bicycle a 5 mile race are the forces of physics. Without them, every time you kicked a soccer ball, the ball would keep going, forever.



force       force



  1. power, energy, or physical strength.

The force of the wind knocked down the trees.

  1. a group of people with a common goal or activity.

She is a member of the police force.


  1. to make or cause to do something by using strength or power.

Ivan forced her to tell the truth.

Advanced Definition


  1. active power, energy, or physical strength.

The force of the hurricane knocked down the trees.

  1. the use of such power, energy, or strength.

The enemy took the castle by force.

  1. someone or something with the capacity to influence or cause change.

The force of logic eventually convinced the committee.

A group of parents was the main force behind the change in the town’s speed limit.

She believed that, as a politician, she could be a force for good.

  1. in law, illegal violence, as against a person.

Accidental death was ruled out, as use of force on the victim was apparent.

  1. a group of people joined by a common goal or activity. the labor force

the police force

  1. in physics, an influence on the shape, motion, or other characteristics of a body or system.
  2. (often pl.) military troops; army.

The enemy has overpowered our forces in the area.

  1. effective intensity, as of the mind.

transitive verb

  1. to use strength or coercion in order to compel.

The interrogators forced him to tell the truth.

  1. to cause to do something despite resistance or hesitation.

The accident forced her to rely on her family for help.

Being turned down for promotion forced him to make a difficult decision.

  1. to bring about (something) despite there being reluctance or unwillingness.

The scandal forced the congressman’s resignation from office.

Complaints from customers forced the removal of the product from the market.

  1. to obtain through force.

His captors forced a confession from him.

  1. to tax or strain.

Don’t force the situation.

Spanish cognate

fuerza: The Spanish word fuerza means force.

These are some examples of how the word or forms of the word are used:

  1. However, he points out, there are differences. In an actual launch, astronauts feel about three times the force of gravity. Gravity is the force that pulls things toward Earth.
  2. One of the biggest challenges in space is coping with what’s missing: gravity. Gravity is aforce of attraction between two objects that have mass. On Earth, the planet’s massive gravity pulls

you toward it. In the zero gravity of space, tools float away and water droplets drift off, making it almost impossible to perform everyday tasks.

  1. In the next room two boys are playing ping pong. One boy is new to the game and is losing. Every time he hits the ball, he swings the paddle with too much force. The tiny ball has very little mass, but the boy’s fast swing sends it off the table entirely. In this case, the boy is giving the ball too much momentum. Momentum, the quantity of motion in a moving object, is determined by an object’s mass and its velocity.
  2. Keep in mind that force and work are not the same things as energy. Energy comes in several forms. But the best way to understand it is as something that creates the ability to do work. When someone says, “I don’t have any energy,” what do they usually mean? Often, they mean they don’t have the strength or motivation to work.
  3. The central spine of a strandbeest is a plastic crankshaft (rotating rod) that’s linked to all its many legs. Each leg has 11 plastic “bones” that form a mechanical linkage-an assembly of rigid rods and joints that transmits mechanical forces and movement from one place to another. As the crankshaft rotates, it moves a leg joint, which transmits motion via the other joints to the foot.


friction       fric ·tion



  1. the rubbing of one object or surface against another.

If you rub two sticks together, the friction will create heat and sparks.

  1. disagreement between people or groups of people; conflict.

It upsets me that there is so much friction in our family.

Advanced Definition


  1. the rubbing of surfaces against each other.

Oil prevents friction from wearing down engine parts too quickly.

Friction creates heat.

  1. the resistance of a surface to relative motion, as of an object sliding or rolling over it.

When the ice is rough and snowy, there is too much friction to skate well.

  1. conflict between people or groups of people; contention.

Friction between the two countries centers on a dispute over the border.

At our last family gathering, I could sense friction between my mother and my aunt.

Spanish cognate

fricción : The Spanish word fricción means friction.

These are some examples of how the word or forms of the word are used:

  1. Glaciers shape the landscape in a process called erosion. Erosion is the result of the friction of wind, water, or, in this case, ice against rocks and soil. Glaciers changed many landscapes, leaving behind waterfalls and moraines, which are very rocky landscapes created by glacial debris.
  1. Few non-bowlers know that a thin layer of mineral oil is applied to the first two-thirds of a bowling lane. Oil reduces friction, the resistance of objects to sliding. The oil is applied mainly to protect the lanes from damage. But it also has a huge impact on the game because it affects the motion of the ball.
  1. Different materials or where you’re sitting on the roller coaster do actually affect how you experience the potential energy and kinetic energy. Roller coaster tracks made of steel, as opposed to wood, can create less friction and therefore offer a smoother ride. This means that the potential and kinetic energies created are delivered more efficiently to the roller coaster and ultimately, to you.
  2. Turning the pin adjusts the tension on the string, which, in turn, adjusts the pitch. “The real skill is in making it stay there,” says Gordon. There’s a lot of tension andfriction in the strings and its surroundings. “The challenge is to leave the tuning pin in a position so that when someone hits the piano really hard, they’re not gonna knock it out of tune.”
  3. He kicked his legs out. He kicked them around, running in place. He tried to rub the cold sheets as much as possible to make them warm. This, he had learned in science class, is called friction. Friction makes heat, and he needed as much heat as he could get.


interaction       in ·ter ·ac ·tion

Advanced Definition


  1. action each upon the other or others; reciprocal action, influence, or effect. the group’s social interaction

Spanish cognate

interacción : The Spanish word interacción means interaction.

These are some examples of how the word or forms of the word are used:

  1. Like a multivitamin, laughter brings a range of health benefits into your daily life. Laughing boosts your immune system. Just look at the work of Dr. Lee Berk, of Loma Linda University in California. He is, by the way, a friend of Hunter “Patch” Adams’s. If that name sounds familiar, it’s because Adams is a funny doctor who became so famous that a movie was made about him. His interactions with his patients were like comedy routines.
  2. An ecosystem is a group of living organisms going through their life cycles in a particular environment alongside nonliving things. Ecosystems exist because of the interactions between these living and nonliving things. In other words, plants and animals all need each other so that they can continue living; they even need nonliving parts of ecosystems to survive.
  3. The crystal formations make the cavern’s floor look as if it were covered in ice, and the ceiling’s mix of rock and crystal makes it look like diamonds tossed into a chocolate cake.

These crystals grew-and grew so large-because of some very special interactions between water and heat. The Cave of Crystals sits on top of a large deposit of magma, or super-heated liquid rock.

Name: ___________________________________ Date: _______________
Comprehension Questions
1. Once it is in motion, what does an object like a soccer ball have a natural tendency to do?
A. It has a natural tendency to keep moving.
B. It has a natural tendency to stop.
C. It has a natural tendency to change direction.
D. It has a natural tendency to slow down.
2. What does the author explain in this passage?
A. The author explains the force of friction, using different kinds of music as examples.
B. The author explains the sport of soccer, using examples of current teams and players.
C. The author explains the idea of motion, using different sports as examples.
D. The author explains the importance of bike safety, using helmets as an example.
3. Swimmers wearing full-body suits that reduced underwater friction were able to swim faster than other swimmers.
What evidence from the passage supports this statement?
A. Some swimmers shaved their entire bodies to reduce friction caused by hair and increase their speed.
B. After losing contests by a tenth of a second, some swimmers started ridding their bodies of hair to reduce friction.
C. Swimmers wearing full-body suits swam at the same speed as swimmers wearing shirts and shorts that clung closely to their skin.
D. Swimmers wearing full-body suits began to break world records and started winning all the races.
4. Based on the information in the passage, how can friction be described?
A. Friction can be described as a force that acts on an object in motion and can cause the object to stop.
B. Friction can be described as a force that acts on an object in motion and can cause the object to speed up.
C. Friction can be described as the path an object takes after a force acts on it and causes it to move.
D. Friction can be described as the path an object takes when a force acts on it inside a vacuum.
5. What is the passage mainly about?
A. why swimmers and cyclists move at different speeds
B. the motion of bodies and objects
C. the movement of an object inside a vacuum
D. the scientific discoveries of Sir Isaac Newton
6. Read the following sentence: “Newton suggested that objects like the soccer ball have a natural tendency to keep moving. The only reason they stop, he believed, is because an unbalanced force acts on them.”
What does the word tendency mean?
A. a very small chance of something happening
B. a fifty-fifty chance of something happening
C. the fear of doing something or acting in a certain way
D. the way something normally behaves or acts
7. Choose the answer that best completes the sentence below.
Newton suggested that a ball has a natural tendency to keep moving _______ others
believed that a ball has a natural tendency to stop.
A. although
B. because
C. before
D. later on
8. What are some things cyclists do to reduce friction?
9. According to Newton’s First Law of Motion, what will happen to a soccer ball that is kicked?
10. The end of the passage states that without the forces of physics, every time you kicked a soccer ball or jumped on a bike, the ball and the bike would keep going, forever. Explain why the ball and bike would keep going, using evidence from the passage.
______________________________________________________________________________ · © 2013 ReadWorks®, Inc. All rights reserved.


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