$12 \,kg$ bomb at rest explodes into two pieces of $4 \,kg$ and $8 \,kg$. If the momentum of the $4 \,kg$ piece is $20 \,Ns$, what is the kinetic energy of the $8 \,kg$ piece (in $\,J$)?

$A$ gun fires a bullet of mass $50 \, g$ with a velocity of $30 \, m/s$. Because of this,the gun is pushed back with a velocity of $1 \, m/s$. The mass of the gun is .......... $kg$.

$A$ particle of mass $4 M$ which is initially at rest explodes into three pieces of masses $M, M$ and $2 M$. The equal masses move along $X$ and $Y$-axes with velocities $4 \ m s^{-1}$ and $6 \ m s^{-1}$ respectively. The magnitude of the velocity of the heavier mass is

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

$A$ spacecraft of mass $M$ is moving with a velocity $V$. It suddenly breaks into two parts. One part of mass $m$ comes to rest. What will be the velocity of the other part?

$A$ bomb at rest explodes into $3$ parts of the same mass. The momentum of two parts is $-3 p \hat{i}$ and $2 p \hat{j}$ respectively. The magnitude of the momentum of the third part is