# The viscous force between the layers of liquid is same, then why there is variation in the velocities of its layers?

I have learned in my textbook that when the liquid flows the bottom layer of the liquid never moves because of friction, but the upper layers move with increasing velocities how it is possible if the viscous force between all these layers is same

• The velocity increases with distance from the bottom, but the velocity is constant in time. Since each layer is not accelerating the forces on that layer are in balance, so the force exerted on the layer by the slower layer below must be equal and opposite to the force from the faster layer above. – Michael Jan 24 '13 at 7:58

$$\mbox{Force} \propto \mbox{Velocity Gradient}$$