$A$ body of mass $M_1$ collides elastically with another mass $M_2$ at rest. There is maximum transfer of energy when

Two identical spheres move in opposite directions with speeds $v_1$ and $v_2$ and pass behind an opaque screen,where they may either cross without touching (Event $1$) or make an elastic head-on collision (Event $2$).

$A$ moving particle collides with a stationary particle of mass $\frac{1}{n}$ times the mass of the moving particle. The fraction of its kinetic energy transferred to the stationary particle is:

$A$ body of mass $m$ is at rest. Another body of the same mass moving with velocity $V$ makes a head-on elastic collision with the first body. After the collision,the first body starts to move with velocity:

$A$ ball of mass $m$ moving with speed $u$ undergoes a head-on elastic collision with a stationary ball of mass $nm$. What is the fraction of the kinetic energy transferred to the heavier ball?

$A$ body of mass $m$ moving with velocity $u_1$ collides elastically with another body of the same mass $m$ at rest. After the collision,they move at an angle of .............. $^o$ to each other.