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`.

Options

A. 25 cm
B. 5 cm
C. 10 cm
D. 50 cm

Explanation

`T=(2xx10)/(10)xx(1)/(sqrt(2))=sqrt(2)` sec
`x=v_((x))t`
`=((m u cos theta)/(m_(1)+m_(2)))t = (((1xx10)/(sqrt(2)))sqrt(2))/(100)=0.1 m = 10 cm`