Block `A` of mass `5kg` is placed on long block `B` having a mass of `5kg`. The coefficient of friction between two block is `0.4`. There is no friction between the ground and lower block. The upper block is given a sudden velocity of `10m//s`. The upper block slides toward right, so friction force acting on it will be toward left. Its reaction wall act on the lower block, which will act forward . The friction force absorbs `x` mechanical energy from upper block but supply only `y` mechanical energy to lower block. Due to friction the velocity of upper block reduces and velocity of lower block increases. This will continue till velocity of both the block get equal.

Which curve shows the correct variation of velocity of each block `v//s` time?

Options

A.
B.
C.
D.

Answer

A

Explanation

As kinetic friction force is constant so acceleration of both the blocks will be equal and opposite.