Block `A` of mass `2kg` is placed over a block `B` of mass `8kg` . The combination is placed on a rough horizontal surface. If `g=10ms^(-2)` , coefficient of friction between `B` and floor `=0.5` , coefficient of friction between `B` and floor `=0.5` , coefficient of friction between `A` and `B=0.4` and a horizontal force of `10N` is applied on `8kg` block, then the force of friction between `A` and `B` is.

Options

A. zero
B. 50N
C. 40N
D. 100N

Answer

B

Explanation

Net frictional force between block and surface is
`F=muR=0.5xx10xx10=50N`
Applied force is `10N` and it is less than `50N`.
`:.` System is at rest and no friction between A and B.