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 as shown. The coefficient of static friction between A and B is 0.15.B will begin to slide on A if A is pulled with a force greater than

Answer 1

$N=1g=10newtons$

$f_s=N^{\prime }\mu$

$N^{\prime }=0.2g+g$

$=1.2g=12newtons$

$f_s=\left(12\right)\left(0.15\right)$

$=1.8newtons$

$\therefore$ a force greater than $1.8N$ is required to start sliding between A & B as A is on a friction less surface.