Two billiard balls undergo a head-on collision. Ball $1$ is twice as heavy as ball $2$. Initially,ball $1$ moves with a speed $v$ towards ball $2$ which is at rest. Immediately after the collision,ball $1$ travels at a speed of $v/3$ in the same direction. What type of collision has occurred?

What happens when two identical bodies moving in opposite directions undergo a perfectly elastic collision?

When two bodies collide elastically,then

Which of the following potential energy curves in the figure cannot possibly describe the elastic collision of two billiard balls? Here $r$ is the distance between the centres of the balls.

Two balls of mass $5 \ kg$ are moving in opposite directions with the same speed of $5 \ m/s$. They undergo a head-on elastic collision. Find the final velocity of the balls in $m/s$.

The bob $A$ of a pendulum,released from a horizontal position to the vertical,hits another bob $B$ of the same mass at rest on a table as shown in the figure. If the length of the pendulum is $1\,m$,calculate:
$(a)$ The height to which bob $A$ will rise after the collision.
$(b)$ The speed with which bob $B$ starts moving.
Neglect the size of the bobs and assume the collision to be elastic.