Question

A block of mass m kg is placed on a rough inclined plane. The plane is inclined at $\theta$ with the horizontal. As the angle $\theta$ is increased from $0^{\circ }$ to $ta{n}^{-1}\mu$, contact force between the block and the plane is

• A. $mg$
• B. Perpendicular to surface
• C. Variable
• D. Parallel to surface

Answer 1

The correct option is A $mg$

Till angle of repose, block remains stationary

For $\theta <ta{n}^{-1}\mu$

Block is stationary




$\overrightarrow{N}+\overrightarrow{fr}+\overrightarrow{mg}=0$

$\overrightarrow{N}+\overrightarrow{fr}=-\overrightarrow{mg}$

Contact force $\overrightarrow{C}=\overrightarrow{N}+\overrightarrow{fr}$

$\overrightarrow{C}=-\overrightarrow{mg}$ and $C=mg$