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Andy Roddick Serve



This blog will, as many of you may have expected, examine yet another sports related topic. In this case we will look at another very impressive athletic feat, this being the serve of tennis legend Andy Roddick. Like Chara's slap shot, the serve is composed of multiple different phases, each incorporating a multitude of physics concepts in every small motion. These include the wind-up the toss and the strike, respectively.

As the toss goes up, players press their feet against the court, using ground reaction forces to build up elastic potential energy. Rotations of the legs, hips and shoulders produce maximum angular momentum that the player needs to absolutely smack the ball! As the player leaves the ground, one must display impeccable timing as they transfer the potential from their legs to their striking hand, referred to by some as the kinetic chain principle.

A high, confident toss made 1 to 2 ft. inside the baseline allows the server to uncoil both upward and forward into the court, making contact at 1.5 times body height. For Roddick, at 6 ft. 2 in., that is roughly 9.5 ft. off the ground. The toss is crucial, and takes time to perfect, no matter the level one is competing on.

Then comes the most intense part, the strike!! :worked_till_5am: On a 120-mph serve, the ball is in contact with the racquet strings for about 5 milliseconds, moving up to 5 in. laterally across the string plane, gathering spin. The tip of the racquet moves at nearly 120 mph, though at the point of impact, a few inches closer to the ground, the racquet is moving roughly 22 percent slower. The ball's additional speed comes from both the elastic energy in the rubber, which returns 53 to 58 percent of the force exerted upon it, and the racquet strings (strung at an average of 60 pounds of tension), which stretch about 1 in. during the impact.


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