compression is larger than the impulse during the expansion,
with the result that the ball rebounds at a speed less than the
incident speed. The plasticene ball did not bounce and remained
permanently deformed after the collision. All of the
hysteresis curves have a finite area, indicating that all collisions
were inelastic. The golf and superballs have an approximately
linear compression phase, with F}y, and a nonlinear
expansion phase.
The y displacement wave forms are more closely sinusoidal
than the force wave forms, at least during the compression
phase. In all cases it was found that the ball rebounds
in a compressed state since y remains finite at the end
of the impact. This was confirmed for the tennis and superballs
by aligning the beam L2 , as shown in Fig. 1, so that it
grazed the top of the ball when the ball was at rest on thepiezo. The results for the tennis ball are shown in Fig. 3,
where it can be seen that the beam is blocked just prior to the
impact, it is unblocked during the impact, and remains unblocked
for about 0.5 ms after the impact. The spatial resolution
was not sufficient to observe this effect with the other
balls, since the ball compression was too small.
compression is larger than the impulse during the expansion,with the result that the ball rebounds at a speed less than theincident speed. The plasticene ball did not bounce and remainedpermanently deformed after the collision. All of thehysteresis curves have a finite area, indicating that all collisionswere inelastic. The golf and superballs have an approximatelylinear compression phase, with F}y, and a nonlinearexpansion phase.The y displacement wave forms are more closely sinusoidalthan the force wave forms, at least during the compressionphase. In all cases it was found that the ball reboundsin a compressed state since y remains finite at the endof the impact. This was confirmed for the tennis and superballsby aligning the beam L2 , as shown in Fig. 1, so that itgrazed the top of the ball when the ball was at rest on thepiezo. The results for the tennis ball are shown in Fig. 3,where it can be seen that the beam is blocked just prior to theimpact, it is unblocked during the impact, and remains unblockedfor about 0.5 ms after the impact. The spatial resolutionwas not sufficient to observe this effect with the otherballs, since the ball compression was too small.
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