Question

A block of mass $m$ is moving with a constant acceleration ${}^{\prime }{a}^{\prime }$ on a rough horizontal plane. If the coefficient of friction between the block and ground is $\mu$, the power delivered by the external agent after a time $t$ from the beginning is equal to

• A. $2mat$
• B. $\mu mgat$
• C. $\mu m(a+\mu g)gt$
• D. $m(a+\mu g)at$

Answer 1

The correct option is D $m(a+\mu g)at$

Let F is the force applied by external agent

than Net force om the body =mass $\times$acceleration

$F-\mu mg=ma$

$F=m(\mu g+a)$

velocity of mass at any time 't'

$v=u+at$

$v=at$

power delivered by external agent = $Fv$

=$m(\mu g+a)at$