Post by Tennis Fan on Nov 23, 2006 12:03:36 GMT 8
Did you Auusie know trhat the rules of tennis specify that the ball must bounce to a height between 53 and 58 inches when dropped from a height of 100 inches onto a concrete slab?. What happens in pactual play is hard to predict, but a good test is to drop a ball onto the strings when the head is clamped (eg by placing the racquet on the floor and stepping on the handle near the head). When dropped from a height of say 1 meter, the ball will bounce to a height of about 0.70 meter. The ball loses about 45% of its energy when dropped on concrete, but it loses only 30% of its energy when dropped on the strings. That's because the strings absorb some of the impact energy and then give almost all of that back to the ball. Teh amount of energy lost by the ball depends on its compression. When dropped from 100 inches on concrete, it compresses by about 1/5th inch. When dropped on the strings, it compresses by about 1/6th inch. The bigger the compression, the more energy is lost when the ball expands back to its original shape. That means that at high impact speeds, where the ball compresses more, the energy loss is e ven greater. Furthermore, teh fraction of the ball's energy that is lost also increases as the the ball's energy is increased or as the compression is increase. Thankyou for your attention.
Chris.
