The Concepts Of Physics Applicable In Football

Physics is an incredible broad subject. Physics explains the most astoundingly and most complex concepts in our universe. Physics can, for instance, explain astronomy like how the planets, the stars and how the galaxies operate far, far away from the place we call home earth. Physics can explain how atoms, which many think are the smallest particle in our universe, are in fact built up by even smaller and more complex particles. This frightens many, physics is considered by many to be heavy, and for some, unattainable. However, physics also describes everyday matter. It explains how and what we see and hear. It explains moving or motionless objects. It even explains sports through engineering physics and mechanics. The world’s most played sport, football, is popular for many reasons, but one is because of its simplicity. There is not a lot of equipment required and it’s not a complicated sport, simple and basic rules for both experienced and new people. However, the physics behind football can’t be explained in another way than astounding. There are many factors that influence the behaviour of a football and a big portion of this can be explained through physics. How the ball is hit, with what force, where on the ball it is hit and with what technique affects the behaviour of the ball substantially. These vital factors could determine whether the ball travels 70 meters in the air without contact with the ground, or just travel on the grass for only a few meters. There are also many other factors influencing the behaviour of a football, primarily the weather conditions during the time when the ball gets hit. Wind and the amount of water on the grass does influence how the ball acts and moves after a force has acted upon it.

There are several reasons why this topic was undertaken. First and foremost, there was a personal interested regarding both football, but also the concepts of physics that explain it. Football as a topic offered several options to investigate, whilst at the same time contribute with enjoyment and interest from a personal standpoint. The second reason why this was an interesting topic was the fact that you can create simplified experiments, both regarding performing it, as well as the understanding and the explanation behind the results. This allows you to investigate more complex concepts, whilst at the same time keeping it on an understandable level. The third and probably most important reason is because of one common knowledge amongst football players and people interested in football. The common knowledge is that rainy weather conditions or a wet field affect the movement of the ball quite significantly and increases the velocity of the ball. However, few know how much it does influence the velocity of the ball, as well as the friction coefficient between the football and the grass. There are many who claim they know the results of these conditions. This so called “common knowledge” on this topic justifies why this investigation has value, as it offers a possibility to scientifically confirm, or invalidate these claims. Even though these claims pose questions and speculations, they are vague and unclear in the context of mechanics and engineering physics. To say that the amount of water affects the movement of the football might be true, but the statement is vague and not especially scientific.

In order to create more focused research question based on these claims, it’s important to understand the concepts of mechanics. The football, which has the shape of a sphere has a different motion compared to many other objects. As it moves, the total kinetic energy can be described with this formula: 2 + Ke stands for the kinetic energy, which is the total energy an object possesses due to its motion. The 1st term in the formula (2) is the translational kinetic energy, which is the energy due to an object moving from one position to another. To find the translational kinetic energy of a sphere, you multiply the mass (m) with the velocity (v) squared and thereafter divide the product by 2. The 2nd term of the formula is the rotational kinetic energy, which is the energy because of an object rotating. In order to find the rotational kinetic energy of a sphere, the formula states that the moment of inertia (I) is multiplied with the angular velocity squared, followed by being divided by 2. Moment of inertia is defined with respect to a specific rotation axis.

Objects that have the ability to rotate, like cylinders and spheres, have a distinctive moment of inertia. The moment of inertia of a football, which is a hollow sphere. The angular velocity is the angle swept out by per unit time. When a football rotates, it rotates around its centre of mass, and the angular velocity describes the rate of that rotation. The angular velocity can be found by dividing the velocity with the radius of the sphere. The formula states that the translational kinetic energy (2) is added to the rotational energy) to sum up the total kinetic energy due to motion of the football. The unit for kinetic energy is joules (J).

As the football moves on the grass, the force of friction acts upon the football. This friction force is called kinetic friction or dynamic friction (Ff) and reduces the velocity of the football when it is in contact with the grass. The formula states that the frictional force (Ff) equals the reaction force (R) times the coefficient of dynamic friction. The reaction force (R) is a force explained by Newton’s third law, which states “To every action there is always opposed an equal reaction.” The mass of the football gets acted upon by the gravity of the earth to give the magnitude and vector of the weight of the football. Now, according to Newton’s 3rd law, there has to be an equal and opposite force to the weight of the football, and that is the reaction force. The reaction force has the same magnitude as the weight of the football, but its vector is facing the opposite direction, vertically upwards, instead of the vector of the weight of the football, which has a direction pointing downwards. The coefficient of dynamic friction (is a value, which is found by dividing the force of friction with the normal force. The coefficient of dynamic friction has to have a value between 0 and 1 and depends on the surfaces that are in contact. A high coefficient of dynamic friction leads to a higher friction force acting upon the football as it’s moving across the grass.