Question

If a body is at rest on a horizontal surface which is rough, then

• A. frictional force between body & surface must be zero.
• B. frictional force between body & surface must be non-zero.
• C. frictional force must be less than or equal to ${\mu }_{s}N$ (${\mu }_s$ =coefficient of static friction, N= normal force).
• D. Total contact force must be perpendicular to surface.

Answer 1

The correct option is C frictional force must be less than or equal to ${\mu }_{s}N$ (${\mu }_s$ =coefficient of static friction, N= normal force).

Property of friction: static friction(f) $\le {\mu }_{s}N$