Question

A body is placed on a rough inclined plane of inclination $\theta$. As the angle $\theta$ is increased from $0^{0}to{90}^0$ the contact force between the block and the plane:

• A. remains constant.
• B. decreases.
• C. first decreases then increases.
• D. first increases then decreases.

Answer 1

The correct option is B decreases.

Contact force , $f=\mu N=\mu mg\cos \theta$
When $\theta =0$, $f=\mu mg$
If $\theta$ increases $\cos \theta$ will decrease. So $f$ will decrease with increasing $\theta$.