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

An average force of $125\,N$ is applied on a machine gun firing bullets each of mass $10\,g$ at the speed of $250\,m/s$ to keep it in position. The number of bullets fired per second by the machine gun is:

$A$ particle is acted upon by a force whose components' variations with time are shown in the diagrams. The magnitude of the change in momentum of the particle in $0.1\,s$ is:

Swimming is possible on account of

In projectile motion,two particles of masses $m_1$ and $m_2$ have velocities $\vec{V}_1$ and $\vec{V}_2$ respectively at time $t=0$. Their velocities become $\vec{V}_1^{\prime}$ and $\vec{V}_2^{\prime}$ at time $2t$ while still moving in air. The value of $[(m_1 \vec{V}_1^{\prime} + m_2 \vec{V}_2^{\prime}) - (m_1 \vec{V}_1 + m_2 \vec{V}_2)]$ is ($g =$ acceleration due to gravity).

$A$ ball of mass $150 \, g$ moving with a velocity of $12 \, m/s$ hits a bat and returns with a velocity of $20 \, m/s$ in the opposite direction within $0.01 \, s$. The force exerted by the bat on the ball is ........... $N$.