A man of mass M stands at one end of a stationary plank of length L, lying on a smooth surface. The man walks to the other end of the plank. If the mass of the plank is `M//3`, the distance that the man moves relative to the ground is

Options

A. `(3L)/(4)`
B. `(L)/(4)`
C. `(4L)/(5)`
D. `(L)/(3)`

Answer

B

Explanation

LeT the distance moved by plank is `x`
`m_(1)Deltax_(1)+m_(2)Deltax_(2)=0`
`M(L-x)+(M)/(3)(-x)=0`
`rArr=(3L)/(4)`
`therefore`distance moved by person w.r.t. to goround `=L-x=(L)/(4)`