The principle of conservation of linear momentum can be strictly applied during a collision between two particles provided the time of impact is

$A$ man of mass $m$ is standing on a platform of mass $M$ kept on a smooth ice surface. If the man starts moving on the platform with a speed $v$ relative to the platform,with what velocity does the platform recoil relative to the ice?

$A$ mass of $1 \; kg$ is thrown up with a velocity of $100 \; m/s$. After $5 \; s$,it explodes into two parts. One part of mass $400 \; g$ comes down with a velocity of $25 \; m/s$. Calculate the velocity of the other part.

The momentum of a system is conserved:

$A$ shell of mass $20 \,kg$ at rest explodes into two fragments whose masses are in the ratio $2 : 3$. The smaller fragment moves with a velocity of $6 \,ms^{-1}$. The kinetic energy of the larger fragment is (in $\,J$)

$A$ shell of mass $5 M$, acted upon by no external force and initially at rest, bursts into three fragments of masses $M, 2 M$, and $2 M$ respectively. The first two fragments move in opposite directions with velocities of magnitudes $2 v$ and $v$ respectively. The third fragment will