The wooden bar is kept on an inclined plane. What is the smallest force directed perpendicular to the surface with which you need to press the bar to keep it stationary on it ? Mass of the block m=0.2 kg, the length of the inclined plane l=1m, height H=0.5 m, the coefficient of the block on the plane is `1/(2sqrt(3))`

Options

A. 2N
B. `1/2N`
C. `1/(sqrt(3)) M`
D. `sqrt(3)N`

Answer

C

Explanation

`F+ mg cos theta=N`
`mg sin theta= mu N=mu(F+mg cos theta)`
`F=(mg sin theta-mu mg cos theta)/(mu)`
`=(2[1/2-1/(2sqrt(3))xx(sqrt(3))/2])/(1/(2sqrt(3)))=sqrt(3)N`