question_answer

A block of mass 1kg just remains in equilibrium with the verticle wall of a cart accelerating uniformly with \[20m/{{s}^{2}}\]as shown. The coefficient of friction between block and wall is \[(g=10m/{{s}^{2}})\]:

A)  \[0.1\]                        

B)  \[0.2\]                          

C)  \[0.5\]                                 

D)   \[1\]                    

Correct Answer: C

Solution :

For vertical equilibrium \[\Sigma {{F}_{X}}=0.R=ma\] FBD of mass, m             From FBD, we get                                 \[mg=\mu R=\mu ma\]                                 \[\mu =\frac{g}{a}=0.5\]