Question

Frictional force between solids operates even when they do not move with respect to each other. Do we have viscous force acting between two layers even if there is no relative motion?

Answer 1

Explanation:

• No, we don’t have viscous force acting between two layers when there is no relative motion.
• Viscous force is against the relative motion between the layers of a liquid.  When the liquid is at rest, no layer of liquid is created and so the relative motion also do not exist.
• In solids, the friction force acts due to intermolecular force between the surfaces of two solids.  
• So, there is no need of transitional movement between the solids for the frictional force to exist.  
• Hence, frictional force between solids operates even when there is no movement between them.