question_answer

A block B is pushed momentarily along a horizontal surface with an initial velocity \[v\]. If \[\mu \] is the coefficient of sliding friction between B and the surface, block B will come to rest after a time

A)  \[\frac{g\mu }{v}\]                            

B)  \[\frac{g}{v}\]

C)  \[\frac{v}{g}\]                                   

D)  \[\frac{v}{g\mu }\]

Correct Answer: D

Solution :

 Given, \[\Rightarrow \] final velocity = 0        Using               \[\Delta x=(65+65)-120\] \[\Rightarrow \] \[\Delta x=10\,m\]       \[\frac{\lambda }{2}\] \[\lambda \] (f is the force of friction) Retardation, \[=\left( 10-\frac{\lambda }{2} \right)\] \[=(2n)\frac{\lambda }{2}\]   \[n=0,\,\,1,\,\,2,...\]