Question

A block of mass `m=2kg` is placed in equilibrium on a moving plank accelerating with `a=1m//s^(2)` . If coefficient of friction between plank and block `mu=0.2` . The friction force acting on theblock is:
A. 2N
B. 4N
C. 3N
D. None of these

Answer 1

Correct Answer - A
In this case driving force=ma
`=2xx1=2N`
And resisting force `=f_(lim)=muN=4N`
Hence the mass will not slide over the plank friction should be static nature `f=2N` .