$A$ ball is dropped from height $h$ on a plane. If the coefficient of restitution of the plane is $e$ and the ball hits the ground two times,the height up to which it reaches after two jumps will be:

Derive the expressions for the velocities of two bodies after a one-dimensional elastic collision.

Consider the following statements $A$ and $B$ and identify the correct answer:
$A$. In an elastic collision,if a body suffers a head-on collision with another of the same mass at rest,then the first body comes to rest while the other starts moving with the velocity of the first one.
$B$. Two bodies of equal mass suffering a head-on elastic collision merely exchange their velocities.

$A$ ball of mass $m$ moving with a speed $u$ undergoes a head-on elastic collision with a ball of mass $nm$ initially at rest. The fraction of the incident energy transferred to the heavier ball is

An object of mass $m_{1}$ collides with another object of mass $m_{2}$,which is at rest. After the collision,the objects move with equal speeds in opposite directions. The ratio of the masses $m_{2} : m_{1}$ is

Ball $A$ moving at $12 \ m/s$ collides elastically with ball $B$ (initially at rest) as shown in the figure. If both balls have the same mass, what is the final velocity of ball $A$ in $m/s$?