$A$ shell,in flight,explodes into four unequal parts. Which of the following is conserved?

$A$ body of mass $M$ is at rest. It explodes into three fragments. Two of the fragments,each of mass $M/4$,fly off perpendicular to each other with velocities of $3 \ m/s$ and $4 \ m/s$ respectively. What is the velocity of the third fragment in $m/s$?

Newton's third law of motion leads to the law of conservation of

If the resultant of all the external forces acting on a system of particles is zero,then from an inertial frame,one can surely say that

$A$ system of $N$ particles is free from any external forces. Which of the following is true for the magnitude of the total momentum of the system?

$A$ man of $60\,kg$ is running on the road and suddenly jumps into a stationary trolley car of mass $120\,kg$. Then,the trolley car starts moving with a velocity of $2\,ms^{-1}$. The velocity of the running man when he jumped into the car was . . . . . . $ms^{-1}$.