Question

A block is pushed momentarily on a horizontal surface with initial velocity ‘$v$’. If ‘$μ$’ is the coefficient of sliding friction between the block and surface, the block will come to rest after time (‘$g$’ $=$ acceleration due to gravity)

• A. $\frac{v}{\mu g}$
• B. $\frac{vg}{\mu}$
• C. $\frac{v\mu}{g}$
• D. $\frac{\mu g}{v}$

Answer 1

Answer: (A)

Given, initial velocity $=v$
Final velocity $=0$
Coefficient of fraction $=\mu$
For a straight line motion
$v-u=a t$
Here, $\,\,0-v=-(\mu g) t \,\,\,\,\,$ $\left[\right. As\left.\mu=\frac{a}{g}\right]$
Negative sign indicates retardation
$\Rightarrow \,\,\,t=\frac{V}{\mu g}$