question_answer

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

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

B) (b)\[\frac{\mu g}{v}\]

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

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

Correct Answer: A

Solution :

[c] Velocity of sound in gas \[ma={{f}_{r}}\] \[ma=\mu \,mg\therefore R=mg\] \[a=\mu g\] Since block comes to rest \[{{V}_{f}}=0\] \[{{V}_{f}}-u=-at\,\,\therefore -\,ve\,sign\,for\,retardation\] \[0-V=-\mu gt\] \[t=\frac{v}{\mu g}\]