$A$ body falling on the ground from a height of $10 \, m$,rebounds to a height of $2.5 \, m$. The ratio of the velocities of the body just before and after the collision will be:

Six steel balls of identical size are lined up along a straight frictionless groove. Two similar balls moving with a speed $V$ along the groove collide with this row on the extreme left end. Then:

$A$ ball $A$ of mass $m$ moving along the positive $x$-direction with kinetic energy $K$ and momentum $p$ undergoes an elastic head-on collision with a stationary ball $B$ of mass $M$. After the collision,the ball $A$ moves along the negative $x$-direction with kinetic energy $K/9$. The final momentum of $B$ is:

What percentage of kinetic energy of a moving particle is transferred to a stationary particle when it strikes the stationary particle of $5$ times its mass (in $\%$)? (Assume the collision to be head-on elastic collision)

$A$ steel ball of radius $2 \,cm$ is at rest on a frictionless surface. Another steel ball of radius $4 \,cm$ moving with velocity of $81 \,cm \,s^{-1}$ collides elastically with the ball which is at rest. After collision, the ball with radius of $2 \,cm$ moves with a speed of:

In a scattering experiment,a particle of mass $2m$ collides with another particle of mass $m$,which is initially at rest. Assuming the collision to be perfectly elastic,the maximum angular deviation $\theta$ of the heavier particle,as shown in the figure,in radians is: