Fluid friction, also known as viscous drag or internal resistance, is a type of friction that occurs between layers of a moving fluid. It is caused by the viscosity of the fluid, which can be described as its "thickness". Liquids and gases are both considered fluids.
The force of fluid friction can be experienced when an object moves through air, water, or other gases and liquids. The magnitude of fluid friction depends on several factors, including the area of contact between the surface and the fluid, the velocity gradient of the substance, and the coefficient of fluid friction or eta (η).
