Question

Three balls A, B and C of the same mass '$m$' are placed on a frictioneless horizontal plane in a straight line as shown. Ball A is moved with velocity $u$ towards the middle ball $B$. If all the collisions are elastic, find the final velocities of all the balls.

Answer 1

A collides elastically with B and comes to rest but B starts moving with velocity $u$.

After a while $B$ collides elastically with $C$ and comes to rest but $C$ starts moving with velocity $u$.

Therefore, final velocities, $V_A=0,V_B=0$ and $V_C=u$.