A body is slowly lowered onto a massive platform moving horizontally.at a speed of 4 m/s. Through what distance will the body slide relative to the platform? (The coefficient of friction is `0.2,g=10 m//m^2`)

Options

A. `4 m`
B. `2 m`
C. `16 m`
D. `8 m`

Answer

A

Explanation

The frictional force between the body and the platform ` = mu mg`, where m is the mass of the body.
Initially the relative velocity=4m/s.
The relative retardation `= mu g = 0.2 xx 10 = 2 m//s^2`.
If S is the relative displacement before the relative velocity becomes zero, we have
`0 = 4^2 - 2 xx 2 xxS`
`S = 16/4 = 4m`