question_answer

A boy of mass m is sliding down a vertical pole by pressing it with a horizontal force F. If u. is the coefficient of friction between his palm & the pole, the acceleration with which he slides down is

A)  1                                            

B) \[\frac{\mu F}{m}\]

C) \[g+\frac{\mu F}{m}\]                  

D) \[g-\frac{\mu F}{m}\]

Correct Answer: D

Solution :

Here normal contact force N = F friction force, \[f=\mu N=\mu F\] So the FBD of boy is ma = mg-f\[\Rightarrow \]\[a=g-\frac{\mu F}{m}\]