question_answer

A block of mass 2 kg is pressed against a rough wall as shown in the figure. The friction between the wall and block is [Take\[g=10\,m/{{s}^{2}}\]]

A)  60 N                     

B)  50 N

C)  30 N                     

D)  20 N

Correct Answer: D

Solution :

 Free Body Diagram of 2 kg block is shown below. The limiting value of friction force is, \[{{f}_{L}}={{\mu }_{s}}N=0.6\times 100=60\,N\] But the force applied is 20 N only, so friction is static in nature and its value is equal to \[f(=)20\text{N}.\]