Cannon of mass 5m (having a shell of mass m) is at rest on a smooth horizontal ground fires the shell with its barrel at an angle A with the horizontal at a velocity u relative to the cannon. Find the horizontal distance of the point where shell hits the ground from the original position of the cannon

Ans) Since initial momentum is 0 final must also be,

Relative=u

Hence absolute=u + v...where v=recoil velocity,

 4m.v=m (u+v)

 v=u/3

Hence initial velocity= u + u/3 = 4u/3

And angle of projection=A

Hence Range= 16 u^2 sin2A