The quantity that is not conserved in an inelastic collision is

$A$ ball of mass $10 \text{ g}$ is allowed to fall from a height of $10 \text{ m}$. After the collision with the ground, if $50\%$ of its energy is lost, then the height reached by the ball is: (in $\text{ m}$)

$A$ particle of mass $m$ collides with another stationary particle of mass $M$. The particle of mass $m$ stops just after the collision. The coefficient of restitution is

In the figure shown,a small ball hits obliquely a smooth and horizontal surface with speed $u$ whose $x$ and $y$ components are indicated. If the coefficient of restitution is $\frac{1}{2}$,then its $x$ and $y$ components $v_x$ and $v_y$ just after collision are respectively

$A$ rubber ball is released from a height of $5\, m$ above the floor. It bounces back repeatedly,always rising to $\frac{81}{100}$ of the height through which it falls. Find the average speed of the ball. (Take $g = 10\, m/s^2$)

$A$ wooden block of mass $m$ moves with velocity $v$ and collides with another block of mass $4m$,which is at rest. After the collision,the block of mass $m$ comes to rest. The coefficient of restitution will be: