A block A is placed over a long rough plank B same mass as shown below. The plank is placed over a smooth horizontal surface. At time `t = 0`, block A is given a velocity `v_(0)` in horizontal direction. Let `v_(1)` and `v_(2)` be the velocity of A & B at time 't'. Then choose the correct graph between `v_(1)` or `v_(2)` and t.

Options

A.
B.
C.
D.

Answer

B

Explanation

Friction force between A and B ( = `mu` mg) will accelerate B and retard A till slipping is stopped between the two and since mass of both are equal .
acceleration of B = retardation of A = `mug`
`v_(1) = v_(0) - mu "gt"` and `v_(2) = mu` gt
Hence , the correct graph is B . when the slipping is ceased the common velocity of both blocks becomes `v_(0)//2`