$A$ body of mass $10 \, kg$ at rest is acted upon simultaneously by two forces $4 \, N$ and $3 \, N$ at right angles to each other. The kinetic energy of the body at the end of $10 \, s$ is .............. $J$.

Fill in the blanks:
$(a)$ When an object is lifted from the ground to a certain height,the work done against the gravitational force is ......
$(b)$ When the work done is zero,the speed of the object remains ..........
$(c)$ For a .......... collision,the coefficient of restitution is $1$.

$A$ rifle bullet loses $\left(\frac{1}{20}\right)^{th}$ of its velocity in passing through a plank. Assuming that the plank exerts a constant retarding force, the least number of such planks required just to stop the bullet is .............

The linear momentum of a body of mass $8 \ kg$ is $24 \ kg \ m \ s^{-1}$. If a constant force of $24 \ N$ acts on the body in the direction of motion of the body for a time of $3 \ s$,then the increase in the kinetic energy of the body is (in $J$)

$A$ wooden block of mass $M$ is suspended by a cord and is at rest. $A$ bullet of mass $m$,moving with a velocity $v$,passes through the block and emerges with a velocity $v/2$ in the same direction. If the block rises to a height $h$,calculate the value of $h$.

$A$ ball of mass $1\,kg$ moving with a velocity of $4\,m/s$ collides with a stationary ball of mass $M$. The collision is oblique. After the collision,the first ball moves at a right angle to its initial direction with a velocity of $3\,m/s$. The momentum of the second ball (in $kg\cdot m/s$) after the collision would be nearly: