Question

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

• A. $2.0$
• B. $4.0$
• C. $1.6$
• D. $2.5$

Answer 1

The correct option is A $2.0$

Since the entire system is at rest, so following the FBD

balancing the force along the surface of the Inclined Plane, we get

$mg\sin {30}^o=f$

$m=f/gsin{30}^o=10/\left(10X0.5\right)$

$m=2kg$