Question

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

• A. 0.5 kg
• B. 2 kg
• C. 5 kg
• D. 20 kg

Answer 1

The correct option is B 2 kg

For any object which rests on rough inclined plane,
mgsin$\theta$ = frictional force(f)
$\Rightarrow$ m(10) sin ${30}^{\circ }$ = 10
$\Rightarrow$ m = 2 kg