Question

A block of mass 'm' rests on a rough inclined plane making an angle ${30}^o$ with the horizontal. The coefficient of static friction between the block and the plane is $0.8$. If force of friction on the block is $10$N, the mass of the block is? $(g=10m/s^2)$

• A. $0.2$ kg
• B. $0.4$ kg
• C. $0.8$ kg
• D. $2$ kg

Answer 1

The correct option is D $2$ kg

Given : $\mu =0.8$ $\theta ={30}^o$

Force of static friction $f=10N$

Using $f=mgsin\theta$

$10=m\times 10\times sin\left(30\right)$

$10=m\times 10\times 0.5$

$⟹m=2kg$