Question

A body A of mass 1 kg rests on a smooth surface . another body b of mass 0.2 kg is placed over A . The coefficient of static friction between A and B is 0.15 B will begin on A if A is pulled with a force greater than

a) 1.764 N
b) 0.1764 N
c) 0.3N
d) it will not slide for any F.

give answer with reason...
Please help me.

Answer 1

Take g = 10

The frictional force acting on B is :

F = ωmg

Where ω = coefficient of friction.

m = mass of B.

g = acceleration due to gravity.

Doing the substitution :

F = 0.15 × 0.2 × 10 = 0.3

= 0.3 N

For B to move, a force that is more than the frictional force should be applied since friction acts in the opposite direction of motion hence causing resistance to motion.

We therefore should apply a force more than 0.3 N.