In the elastic collision of objects,

An object $A$ of mass $20 \ kg$ and travelling at $20 \ m \ s^{-1}$ crashes into another object $B$ of mass $200 \ kg$ and travelling at $10 \ m \ s^{-1}$,in the same direction. After the collision,object $A$ bounces back in the opposite direction at a speed of $10 \ m \ s^{-1}$. The speed of the object $B$ after the collision is: (in $m \ s^{-1}$)

$A$ sphere of mass $M$ moving with velocity $u$ undergoes a perfectly elastic head-on collision with another sphere of mass $m$ at rest. After the collision,their velocities are $V$ and $v$ respectively. Find the value of $v$.

$A$ body of mass $M$ moves with velocity $v$ and collides elastically with another body of mass $m$ $(M >> m)$ at rest. Then,the velocity of the body of mass $m$ is:

$A$ smooth sphere of mass $M$ moving with velocity $u$ directly collides elastically with another sphere of mass $m$ at rest. After collision,their final velocities are $V$ and $v$ respectively. The value of $v$ is

$A$ small particle elastically strikes a fixed smooth sphere of $4 \, cm$ radius,with a speed of $5 \, m/s$. The impact parameter for the collision is $2\sqrt{3} \, cm$. Calculate the angle of deflection of the particle ............... $^o$