Laws of Motion - Result Question 45
45. 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
[2007]
(a) $g \mu / V$
(b) $g / V$
(c) $V / g$
(d) $V /(g \mu)$.
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Answer:
Correct Answer: 45. (d)
Solution:
- (d) Friction is the retarding force for the block
$F=m a=\mu R=\mu mg$
Therefore, from the first equation of motion
$v=u-a t$
$0=V-\mu g \times t \Rightarrow \frac{V}{\mu g}=t$
