$A$ ball is moving with velocity $4 \ m/s$ and collides head-on with another stationary ball of double the mass. If the coefficient of restitution is $0.2$,then their velocities (in $m/s$) after the collision will be:

$A$ particle of mass $m$ strikes the ground inelastically with a coefficient of restitution $e$. Find the relation between the angles $\theta$ and $\alpha$ as shown in the figure.

$A$ ball $P$ collides with another identical ball $Q$ at rest. For what value of the coefficient of restitution $e$ will the velocity of ball $Q$ become two times that of ball $P$ after the collision?

Hail stones are observed to strike the surface of a frozen lake at $30^{\circ}$ with the vertical and rebound at $60^{\circ}$ with the vertical. Assuming the contact to be smooth,the coefficient of restitution is

$A$ body is dropped on the ground from a height $h_1$ and after hitting the ground,it rebounds to a height $h_2$. If the ratio of velocities of the body just before and after hitting the ground is $4$,then the percentage loss in kinetic energy of the body is $\frac{x}{4}$. The value of $x$ is $.......$

$A$ ball falls vertically onto a floor with momentum $p$ and then bounces repeatedly. If the coefficient of restitution is $e$, then the total momentum imparted by the ball on the floor is: