question_answer

What is the maximum value of the force F such that the block shown in the arrangement, does not move                                                 [IIT-JEE Screening 2003]

A)                                       20 N                      

B)                 10 N                

C)                 12 N                      

D)                 15 N

Correct Answer: A

Solution :

                                                    \[f=\mu R\]                 \[F\cos 60{}^\circ =\mu (W+F\sin 60{}^\circ )\]                 Substituting \[\mu =\frac{1}{2\sqrt{3}}\] & \[W=10\sqrt{3}\]we get \[F=20N\]