Question

A body is projected along a rough horizontal surface with a velocity $6\text{m/s}$. If the body comes to rest after travelling $9\text{m}$, then coefficient of sliding friction, is ($g=10{\text{m/s}}^2$)

• A. $0.5$
• B. $0.4$
• C. $0.6$
• D. $0.2$

Answer 1

The correct option is D $0.2$

Using newton's 2nd law
$F_{\text{net}}=ma$
Retardation $a=\frac{\mu mg}{m}=\mu g=10\mu$
Now,
$v^2=u^2+2as$
or $0=(6{)}^2-2(10\mu \left)\right(9)$ (since acceleration is negative)
$\therefore \mu =0.2$