question_answer

A cart of mass M has a block of mass m attached to it as shown in fig. The coefficient of friction between the block and the cart is u. What is the minimum acceleration of the cart so that the block m does not fall?

A) \[\mu g\]                                   

B) \[g/\mu \]

C) \[\mu /g\]                      

D) \[M\mu g\text{/}m\]

Correct Answer: B

Solution :

See fig.

If a=acceleration of the cart. Then N=ma

\[\therefore \]\[\mu N=mg\] or \[\mu \,ma=mg\] or  \[a=g/\mu \]