Question

two block A 2kg and B 5kg rest one over the other on a smooth horizontal surface the coefficient of static and dynamic friction between A and B is the same and equal to 0.6 the maximum horizontal force that can be applied to be in order that both A and B do not have any relative motion.
a) 42N
b) 42kgf
c) 5.4kgf
d)1.2N​

Answer 1

Answer:42N

Explanation:

If B rests on top of A , then frictional force between A and B = 5×10×0.6=30N . Max possible acceleration for B due to friction = 30/5= 6m/s^2 . so we can apply a force which will produce a maximum acceleration of 6m/s^2 on A so that they can move t.ogether .until there is a Max acceleration of 6m/s2 , A and B behave like one body. F = (2+5)×6 = 42N.

If u try A rests on B then also answer is same . then also Max acceleration will be 6m/s2 , so answer will be 42 N only