A block A of mass 2 kg rests on another block B of mass 8 kg which rests on a horizontal floor. The coeffici of friction between A and B is 0.2, while that between B and floor is 0.5. When a horizontal force of 25 N applied on the block B, the force of friction between A and B is

Options

A. Zero
B. 3.9 N
C. 5.0 N
D. 49 N

Answer

A

Explanation

`F_l` between block B and surface
`F_(BS)=mu_(BS).R = 0.5(m+M)g = 0.5(2+8)10=50` N, nut the applied force in 25 N. So the lower block will not move therefore there is no pseudo force on upper block A. Hance there will be no force friction between A and B