Question

A block of mass $m$ is pulled slowly by a minimum constant force $\left(F\right)$ on a horizontal surface through a distance $x$. The coefficient of kinetic friction is $\mu$. Find the work done by the force $\left(F\right)$

Answer 1

Apply Energy theorem,

$W_{net}=△K.E$

But, according to question object is moved slowly.

$\therefore △K.E=0$

$\because {\omega }_{net}={\omega }_f+{\omega }_{friction}$

${\omega }_{friction}=-\mu mgx$

$\therefore {\omega }_F-\mu mgx=0$

${\omega }_F=\mu mgx$