Physics of Tennis

When observing a tennis match, one may notice that all three of Newton’s laws are in action.  Newton’s first law states that an object at rest stays at rest and an object in motion stays in motion at the same speed, with the same direction unless acted upon by an unbalanced force.  Using a tennis racket to strike a tennis ball is a prime example of unbalanced force acting upon an object in motion.  Once the ball is struck it flies over the net before being pulled down towards the ground by gravitational pull.  If it weren’t for gravity’s existence, the tennis ball would continue to fly in a straight line forever.  Newton’s second law suggests that force is equal to mass times acceleration.   A serve illustrates the equation that Newton was speaking about.  Take the weight of a tennis player’s racket and multiply it by the speed at which a player swings their racquet and you will have figured out the total amount of force that was exerted by the tennis racket onto the ball.  Newton’s third law suggested that for every action there is an equal and opposite reaction.  Whenever a tennis player strikes a ball the force of the racquet striking the ball and the force of the ball striking the racquet both act upon each other.

Similar to what I talked about in my blog focusing on the physics of hitting a baseball with a bat, tennis racquets also have sweet spots.  The sweet spot is the spot on the racquet that when hit feels the smoothest on the player’s hands.  Also similar to what we talked about regarding baseball, when a tennis player strikes a ball far from the sweet spot the player experiences an uncomfortable vibration that runs through his racquet and onto his hands.  During a serve, kinetic energy is stored in the form of motion as the ball travels through the air.  For this reason, players are capable of serving their hardest when they strike their serve at its peak when tossed up in the air.  This maximizes the use of gravitation potential energy, or the energy stored in the form of height.  Most tennis players attempt to use different forms of topspin, backspin, and sidespin when they hit their shots.  The friction between the ball and the racquet’s strings is responsible for causing the ball to spin forward. (1) Professional tennis players often slide their racquets over the ball to put topspin on their shots.  On the contrary, players are capable of putting backspin on their shots by performing a slicing motion.

1) http://www.unc.edu/~sheng1/spin.htm