A boy of mass `60kg` is standing over a platform of mass `40kg` placed over a smooth horizontal surface. He throws a stone of mass `1kg` with velocity `v=10m//s` at an angle of `45^@` with respect to the ground. Find the displacement of the platform (with boy) on the horizontal surface when the stone lands on the ground. Take `g=10m//s^2`.

Explanation

`1 u cos 45^(@)=(60+40)v , v=(1)/(10sqrt(2))`
Time of flight `= T_(f)=(2u sin theta)/(g)=sqrt(2)sec`.
`S= v xx T_(f)=0.1 m`