Question
What is a viscous force? How does it originate?
Answer
Viscous force is the force that opposes relative motion between adjacent layers of fluid that are in contact with each other.
It originates from the internal friction between the molecules of the fluid. When layers of fluid move relative to each other, the molecules in one layer interact with the molecules in the adjacent layer. These interactions create attractive and repulsive forces between the molecules, which resist the motion of the layers and generate the viscous force.
