Question

A block a of mass 2 kg rests on another block b of mass 8 kg which rests on a horizontal floor. the coefficient of friction between a and b is 0.2 while that between b and floor is 0.5. when a horizontal force 25 n is applied on the block b, the force of friction between a and b is:

Answer 1

Block B together with block A is lying on rough surface with coefficient of friction=0.5.

(coefficient of friction) x (mA+mB)x g
=0.5x10x10=50 N.
So frictional force= 0