What Is the Physics Behind Soccer?

A variety of physics phenomena takes place during a soccer match. For example, each kick demonstrates Newton's three laws of motion. The frequent curving or bending of a ball in flight is caused by a dynamic known as Magnus force.

Newton's first law states that an object at rest tends to stay at rest unless an outside force is exerted on it. In soccer, the outside force is a player's foot or head striking the soccer ball. The first law goes on to say that unless an outside force intervenes, an object in motion tends to stay in motion. The outside forces on the moving soccer ball are friction from the ground and/or air plus Earth's own gravitational pull.

Newton's second law determines the amount of force needed to move the soccer ball. An object with greater mass requires greater force to move. Force is calculated by multiplying the mass of an object by its acceleration. Therefore, the player modifies the force applied to the ball by increasing or decreasing the acceleration of his body. This in turn, sets the acceleration of the ball.

The third law dictates that for every action there is an equal and opposite reaction. In soccer, as the player kicks the ball, the ball pushes back with equal force. The player's greater mass means that the ball's force is relatively weak. This is why players don't fly backwards when they strike the ball.

Magnus force is responsible for some of soccer's greatest highlights. Magnus force is created by adding spin to the ball as it is struck. Soccer players do this by hitting the ball off center. The spinning motion forms a thin layer of atmosphere that clings to the ball. This layer collides with the oncoming air and creates a high-pressure area. At the opposite side, a low-pressure area forms. The ball moves from the high to low areas. If the low-pressure area is on the side of the ball, the ball curves to that side.