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

• A. 1.764 N
• B. 0.1764 N
• C. 0.3 N
• D. It will not slide for any F

Answer 1

Answer: (A)

1.764 N

Answer 2

B will begin to slide on A if Pseudo force is more than limiting friction

$F' > F_{l}$⇒ $m\left( \frac{F}{m + M} \right) > \mu_{s}R$ ⇒$m\left( \frac{F}{m + M} \right) > 0.15mg$

$\therefore F > 1.764N$