Two billiard balls of mass $0.05\,kg$ each moving in opposite directions with $10\,ms ^{-1}$ collide and rebound with the same speed. If the time duration of contact is $t=0.005\,s$, then $\dots N$is the force exerted on the ball due to each other.

A bullet of mass $40 \,g$ is fired from a gun of mass $10 \,kg$. If velocity of bullet is $400 \,m / s$, then the recoil velocity of the gun will be ..........

A gun fires a bullet of mass $50 \,gm$ with a velocity of $30\,m\,{\sec ^{ - 1}}$. Because of this the gun is pushed back with a velocity of $1\,m\,{\sec ^{ - 1}}$. The mass of the gun is .......... $kg$

A bullet mass $10\, gm$ is fired from a gun of mass $1\,kg$. If the recoil velocity is $5\, m/s$, the velocity of the muzzle is ........ $m/s$

A body of mass $M$ at rest explodes into three pieces, two of which of mass $M/4$ each are thrown off in perpendicular directions with velocities of $3\, m/s$ and $4\, m/s$ respectively. The third piece will be thrown off with a velocity of .......... $m/s$

Particle $A$ of mass $m _{1}$ moving with velocity $(\sqrt{3} \hat{i}+\hat{j})\, ms ^{-1}$ collides with another particle $B$ of mass $m _{2}$ which is at rest initially. Let $\overrightarrow{ V }_{1}$ and $\overrightarrow{ V }_{2}$ be the velocities of particles $A$ and $B$ after collision respectively. If $m _{1}=2\, m _{2}$ and after collision $\overrightarrow{ V }_{1}=(\hat{ i }+\sqrt{3} \hat{ j })\, ms ^{-1},$ the angle between $\overrightarrow{ V }_{1}$ and $\overrightarrow{ V }_{2}$ is$......^o$