$A$ body of mass $5\; kg$ is moving with a momentum of $10\; kg\; m/s$. $A$ force of $0.2\; N$ acts on it in the direction of motion of the body for $10\; s$. Find the increase in its kinetic energy. (in $; J$)

$A$ 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 .............

$A$ bullet of mass $30 \,g$ moving with $700 \,ms^{-1}$ collides with a block of mass $4 \,kg$ hanging by a string of length $0.4 \,m$. After the collision, the block rises to a height of $0.2 \,m$. Find the velocity of the bullet when it emerges from the block. (in $\,ms^{-1}$)

Consider the following statements $A$ and $B$. Identify the correct choice in the given answers.
$A$. In an inelastic collision,there is no loss in kinetic energy during collision.
$B$. During a collision,the linear momentum of the entire system of particles is conserved if there is no external force acting on the system.

$A$ mass of $1 \; kg$ collides elastically with a stationary mass of $5 \; kg$. After the collision,the $1 \; kg$ mass moves in the opposite direction with a velocity of $2 \; ms^{-1}$. Which of the following statements is correct for this system of two masses?

$A$ wooden block of mass $M$ rests on a horizontal surface. $A$ bullet of mass $m$ moving in the horizontal direction strikes and gets embedded in it. The combined system covers a distance $x$ on the surface. If the coefficient of friction between the wood and the surface is $\mu$,the speed of the bullet at the time of striking the block is: