Question

An object of mass (m) is located on the horizontal plane at the origin O. The body acquires horizontal velocity V. The mean power developed by the frictional force during the whole time of motion is ($\mu$ = frictional coefficient)-

• A. $\mu mgV$
• B. $\frac{1}{2}\mu mgV$
• C. $\mu mg\frac{V}{4}$
• D. $\frac{3}{2}\mu mgV$

Answer 1

The correct option is B $\frac{1}{2}\mu mgV$

$\begin{array}{c}{v}_i=v\\ v_f=0\\ \Delta k=\frac{1}{2}m{v}^2\\ a=\mu g\\ t=\frac{v}{\mu g}\\ \therefore p=\frac{\Delta k}{t}=\frac{1}{2}m{v}^2\cdot \frac{\mu g}{v}\\ =\frac{mv\mu g}{2}\end{array}$

Hence,

option $\left(B\right)$ is correct answer.