Ball 1 collides with another identical ball at rest. For what value of coefficient of restitution e, the velocity of second ball becomes two times that of 1 after collision? _____.

Explanation

Here `m_(1)=m_(2)` and `u_(2)=0`.
After collision, `v_(2)=((1+e)/(2))u` and
`v_(1)=((1-e)/(2))"u Given," v_(2)=2v_(1)`
on solving we get, `e=(1)/(3)`