A long conveyer belt moves with a constant velocity of `8 ms^(-1)`.Two blockA and B each of mass `2kg` are placed gently on the belt with B on A, initail velocity of block is zero Coefficient of friction between A and belt is `0.1` There is no friction between A and B length of A is `4m`

Find the time when A falls off A initially ,B is no the right and of A lgnore the dimensions of B

Options

A. `1 s`
B. `3s`
C. `2s`
D. `4s`

Answer

c

Explanation

Since there is no friction between A and B ,B will remain at rest

`f_(k) = mu(2 + 2)g = 0.1 (2 +2)g = 4N`
Acceleration of A ` a = (f_(k))/(m) = (4)/(2) = 2ms^(-2)`
For B to fall off A : `ut = (1)/(2)at^(2)`
`rArr 4 = 0 xx t + (1)/(2) 2t^(2) rArr t = 2s`