Physics of Soccer

The sport of soccer has played a huge part of my life since I could remember. Beginning at the age of 5, I began to play recreationally and loved it. Taking in that it was apart of my small town's culture for everyone and their dog to play soccer, it was no question that I would begin at such a young age. However, as we grew older and players began to be weeded out or shift their focus to other sports and activities, I remained loyal to the game and played until I was 17 years old.

Being that this a sport that depends on the idea of kicking a ball into a net to get points, I wanted to dive a little deeper into the basics of how it is possible to even play this sport using concepts from physics.

The game of soccer itself is a team sport with 11 players playing on the field for each team, making that 22 players playing at any point over the course of the game. The sport requires both mental and physical ability, as it requires skill, strategy, speed and strength. The overall purpose is to score as many points possible by kicking the ball into the opposing team's goal, whoever has the most points by the end of the regulation time wins. Now, since Newton is known for his large part in contributing to our fundamental knowledge of physics, it makes sense that his laws would carry over into the basics of soccer.

Newton's three laws are known as Newton's 1st, 2nd, and 3rd law. The 1st law says, an object that is free from all outside forces travels at a constant velocity, covering equal distances in equal times along a straight-line path (How Things Work). The 2nd is, an object's acceleration is equal to the force exerted on that object divided by the object's mass. The equality can be manipulated algebraically to state that the force on the object is equal to the product of the object's mass times its acceleration (How). The 3rd states, For every force that one object exerts on a second object, there is an equal by oppositely directed force that the second object exerts on the first (How).

It is also vital to acknowledge that the concept of friction is a recurring element in these laws. Friction is, the force that resists relative motion between two surfaces in contact. Frictional forces are exerted parallel to the surfaces in the directions opposing their relative motion (How). As we see Newton's 1st law applied in the sport, spectators can see that if no outside forces are applied to the ball, then it will continue moving at the same speed and direction it was before. Knowing that friction is always at work, we know that it will not be the same speed like mentioned in the 1st law, but it will remain in the same direction unless intercepted by another player or obstacle on the field.

Newton's 2nd law is observed when kicking a soccer ball which, notably, occurs quite often. When applying the force of the players foot on the ball, the force causes it to change its speed whether that is from stagnancy to tens of miles per hour, or slowing or speeding the ball's speed up from the first touch. It is important to note that once the ball leaves the player's foot after being kicked, it immediately decelerates no matter what the force applied was as it is instantly affected by friction.

The 3rd law is seen most at work when the spectator's take a closer look at the player's required uniform. Soccer players are required to wear cleats as apart of their uniform. Having cleats at the bottom of their shoes allows the players not only to prevent slipping, but move more quickly since the cleats can cut through the friction applied to them from the grass allowing them to go faster. Newton's 3rd law can be seen at work here since when the cleats are implanted in the ground for that brief moment of time when moving throughout the game, there is equal force applied from the cleats to the ground and the force from the ground being applied to the cleats (The physics behind Soccer Kicks).

When taking all three laws into account when playing the beautiful game, it is also important to remember that friction is a key element as well in the sport. This is since the force applied to the soccer ball needs to be applied with quick, good judgement because due to friction applied to the ball from the ground or air it will gradually slow down as it continues to move.

After covering the basics of soccer, it is essential to show how physics can impact the technical side of the game as well. While the technique you can see physics at work with most ease is known as the banana kick(The Physics), you cannot cover this without further explanation of how to lead up to this advanced move. First of all, the two ways to kick a ball are known as toe kicks and sidekicks. The names note the part of the foot the player uses to kick the ball with. Sidekicks are typically used more with younger players as it has a larger surface area to kick the ball with and more accuracy for beginners, however it exerts less power on the ball. Toe kicks on the other hand, have less accuracy but more power.

Depending on where you kick the ball, really anywhere outside its center, it can cause the ball to spin on its axis, which leads us into the magnus effect (The Physics), the effect that allows the banana kick to occur. Kicking the ball utilizing this technique can cause it to change direction while in air as it spins more and more rapidly. As this occurs, the ball undergoes a top-spin. It causes the velocity of the air around the top half of the ball to become less than the air velocity of the air around the bottom half (Real). This technique is useful when making large passes from player to player in order to switch the field, or, especially when trying to score a goal because it is a difficult shot for the goalie to judge since its path is largely unpredictable.

The beautiful game demonstrates many of the foundational laws of physics clearly, making hold aspects that are educational while most see it solely for its entertainment value, as it is the most popular sport in the world.. Newton's laws, friction, and the magnus effect all add up to create a game that many have such passion for, including myself. And it is connections like these that make the subject of physics much more tangible and interactive among its students. While there are many facets of the game of soccer that apply the laws of physics, this can also be said for everyday life. Many tasks we perform daily could not be accomplished without the assistance of physics which is something greatly overlooked.

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