Concept:
Friction opposes motion and produces retardation.
Frictional force:
\[
f=\mu N
\]
On a horizontal plane:
\[
N=mg
\]
Hence,
\[
f=\mu mg
\]
Retardation:
\[
a=\frac{f}{m}
\]
\[
=\mu g
\]
Since friction is constant, motion is uniformly retarded.
Using first equation of motion:
\[
v=u-at
\]
At stopping point:
\[
v=0
\]
Step 1: Apply equation of motion.
\[
0=v_0-\mu gt
\]
\[
\mu gt=v_0
\]
\[
t=\frac{v_0}{\mu g}
\]
Therefore,
\[
\boxed{\frac{v_0}{\mu g}}
\]