Question

A body is moving along a rough horizontal surface with an initial velocity $6 \,m/s$. If the body comes to rest after travelling a distance $9 \,m$, then the coefficient of sliding friction will be:

• A. 0.4
• B. 0.2
• C. 0.6
• D. 0.8

Answer 1

Answer: (B)

0.2

Answer 2

From third equation of motion
$v^{2}=u^{2}-2\, a s$
Given, $v=0$ (body comes to rest)
$u=6\, m / s, s=9\, m$
$\therefore 0=(6)^{2}-2 \times a \times 9$
or $a=\frac{36}{18}=2\, m / s ^{2}$
Let coefficient of sliding friction be $\mu$.
Then $a=\mu g$
or $\mu=\frac{a}{g}=\frac{2}{10}=0.2$