Question

A block is pushed momentarily on a horizontal surface with initial velocity $v$. If '$u$' 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. $\frac{v}{ug}$
• B. $\frac{u}{vg}$
• C. $uvg$
• D. None of these

Answer 1

Answer: (A)

$\frac{v}{ug}$

Let $V_f$ be the final velocity and $V_i$ be the initial velocity.
$V_f=V_i-at$
$a=\frac{Force}{Mass}=\frac{\mu mg}{m}=\mu g$
$V_f=V_i-at$
putting values and solving for t gives,
$t=\frac{v}{ug}$