Question

A block rests on a rough inclined plane making an angle of `30^@` 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
A. (a) 1.6
B. (b) 4.0
C. (c) 2.0
D. (d) 2.5

Answer 1

Correct Answer - C

`mg sin theta=f_s` (for body to be at rest)
`implies mxx10xxsin 30^@=10`
`implies mxx5=10impliesm=2.0kg`