The law of conservation of linear momentum is derived by using which of Newton's laws?

$A$ projectile is fired with velocity $u$ at an angle $\theta$ with the horizontal. At the highest point of its trajectory,it splits into three segments of masses $m, m$,and $2m$. The first part falls vertically downward with zero initial velocity,and the second part returns via the same path to the point of projection. The velocity of the third part of mass $2m$ just after the explosion will be:

$A$ bomb of mass $9 \ kg$ explodes into two fragments of masses $3 \ kg$ and $6 \ kg$. If the kinetic energy of the $6 \ kg$ fragment is $120 \ J$,find the kinetic energy of the $3 \ kg$ fragment in $J$.

When two balls at the same temperature collide,which of the following quantities is conserved?

The momentum of a system is conserved:

$A$ projectile of mass $m$ is projected from ground with a speed of $50 \, m/s$ at an angle of $53^{\circ}$ with the horizontal. It breaks up into two equal parts at the highest point of the trajectory. One particle comes to rest immediately after the explosion. The distance between the pieces of the projectile when they reach the ground is: (in $, m$)