Question

A 20 kg block is initially at rest on a rough horizontal surface.A horizontal force of 75 N is required to set the block in motion. After it is in motion, a horizontal force of 60 N is required to keep the block moving with constant speed.The coefficient speed. The coefficient of static friction is

• A. 0.6
• B. 0.44
• C. 0.52
• D. 0.38

Answer 1

The correct option is D 0.38

$\begin{array}{c}m=20kg\\ F=\mu mg\\ or\mu s=\frac{F}{mg}\\ =\frac{75}{20\times 98}\\ =\frac{75}{196}=0.382\end{array}$

Hence, Option $D$ is correct.