Question

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. `(v)/(g mu)`
B. `(g mu)/(v)`
C. `(g)/(v)`
D. `(v)/(g)`

Answer 1

Correct Answer - A
Block `B` will come to rest, if force applied to it will vanish due to frictional force acting between block `B` and surface, i.e., force applied=frictional force
i.e., `mug=ma` implies `a=mug`
Now using `v=u+at`
or `0=v-mugt` implies `t=(t)/(mug)` .