What Is the Velocity of a Massless Ping-Pong Ball After an Elastic Collision?

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SUMMARY

The discussion centers on the elastic collision of a massless Ping-Pong ball with an infinitely massive Ping-Pong paddle moving at 20 m/s. The calculated velocity of the ball after the collision is 40 m/s, derived from the formula v2f = (2(infinite mass)/(infinite mass - 0))*20 m/s. However, the concept of infinite mass complicates the calculation, as it challenges conventional physics principles. The conversation emphasizes the importance of frames of reference in understanding motion and collision dynamics.

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An "infinitely massive" Ping-Pong paddle moving with a velocity of 20 m/s hits
a "massless" Ping-Pong ball at rest. The collision is elastic. What is the velocity of
the ball after the collision?

i get v2f = (2(infinite mass)/(infinite mass - 0))*20m/s = 40m/s

is this correct?? i don't know why I am doubting myself.. its just a weird question lol
 
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Correct answer. I don't follow your calc, though. Usually it just isn't possible to calculate anything sensible when there is an infinite quantity involved.

This question is really about frames of reference. How is it different from a ball moving at 20 m/s relative to a stationary wall?
 

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