question_answer

A horizontal force of 10 N is necessary to just hold a block stationary against a wall. The coefficient of friction between the block and the wall is \[0.2\]. The weight of the block is                                                   [AIEEE 2003]

A)             20 N

B) 50 N

C) 100 N

D) 2 N

Correct Answer: D

Solution :

[d] Let R be the normal contact force by wall on the block

R = 10N, \[{{f}_{L}}\] = w and \[f=\mu R\]

For vertical equilibrium of the block,

\[\mu R=w\]

\[\Rightarrow \] \[w=0.2\times 10=2\,N\]