Question

A block of mass M placed on rough surface of coefficient of friction equal to 3. If F is the (4/5) of the minimum force required to just move. Find out the force exerted by ground on the the block

• A. 2.6 Mg
• B. Mg
• C. 4 Mg
• D. 3.4 Mg

Answer 1

The correct option is A 2.6 Mg

$\begin{array}{c}{F}_{min}=3Mg\\ F=\frac{4}{5}\left(3Mg\right)=\frac{12Mg}{5}\\ \therefore F=\frac{12Mg}{5}=2.4Mg\\ N=Mg\\ Netforce=\sqrt{F^2+N^2}=2.6Mg\end{array}$

Hence,

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