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  Solved  Paper-2003

A)         20 N      

B)       50 N                      

C)       100 N                    

D)       2 N

Correct Answer: D

Solution :

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