"Two balls of the same mass approach each other with a relative velocity of 10 m/s, what is their relative velocity after the collision, which is presumed elastic?"(adsbygoogle = window.adsbygoogle || []).push({});

I assumed that the balls have equal and opposite velocities of 10 m/s.

Should the individual velocities be 5 m/s and -5 m/s (because 10 m/s is the relative velocity)?

When I solved the problem, the balls simply exchanged their velocities.

I said that their relative velocities after the collision are 10 m/s. However, this is wrong because there is only one relative velocity.

I think I have the concept wrong. Please clarify.

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# Homework Help: Relative Velocity after collision

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