Question

A body of mass $40 \,kg$ resting on rough horizontal surface is subjected to a force $P$ which is just enough to start the motion of the body. If $\mu_{s}=5, \mu_{x}=0.4, g=10\, m / s ^{2}$ and the force $P$ is continuously applied on the body, then the acceleration of the body is

• A. zero
• B. $1\, m/s^2$
• C. $2\, m/s^2$
• D. $2 .4 \, m/s^2$

Answer 1

Answer: (B)

Force $P=f_{m}=\mu_{0} m g($ when body is rest $)$
When the body starts moving with acceleration a then
$P-F_{k} =m a $
$\mu_{0} m g-\mu_{k} m g =m a $
$a =\left(\mu_{0}-\mu_{k}\right) g $
$=(0.5-0.4) 10 $
$=0.1 \times 10\, m / s ^{2}=1\, m / s ^{2}$