Question

A viscous fluid is flowing through a cylindrical tube. The velocity distribution of the fluid is best represented by the diagram.
A.
B.
C.
D. None of the above

Answer 1

Hint: The property of a fluid that opposes the relative motion between its different layers is known as viscosity. The force that opposes relative motion between the different layers is known as viscous force.

Complete step by step solution:
Here are three diagrams we have. If we consider the first diagram, it represents the viscous liquid. Viscous liquid means there is a viscous force between the layers of the liquid. The viscous force is comparatively more between solid and liquid layer and as the layers increases in the middle comparatively, the viscous force is less. So, the first option is wrong.

When we consider the second option, near the solid surface, the component of the velocity is more the length is more, and in the middle, the component of velocity is comparatively less. This is also not possible here, at the surface viscous force is more and, in the middle, it is less. Where the viscous force is less there the velocity should be more, but here it is represented as less. Here, the third option represents that, when the viscous force is less, velocity is more and vice versa.

Hence, option C is the correct answer.

Note: Remember that the viscous force and frictional force are similar, but they are not the same. In a moving fluid, the fluid consists of multiple layers. As compared to the neighboring layers each layer has a noticeable difference in speed. This force, called the frictional force, decreases the relative motion between the layers. Viscous force is defined as the force that acts between two layers of a moving fluid.