A projectile of mass $M$ is fired so that the horizontal range is $4 \mathrm{~km}$. At the highest point the…
A projectile of mass $M$ is fired so that the horizontal range is $4 \mathrm{~km}$. At the highest point the projectile explodes in two parts of masses $M / 4$ and $3 M / 4$ respectively and the heavier part starts falling down vertically with zero initial speed. The horizontal range (distance from point of firing) of the lighter part is :