Question

Which of the following is not true regarding frictional resistance in a laminar flow in pipes?
1. Depends on the velocity of flow
2. Dependent on pressure
3. Proportional to the area of surface in contact
4. Is independent of the nature of the contact surface
5. Is affected by the temperature of the flowing fluid

Answer 1

Correct Answer - Option 2 : Dependent on pressure

Concept:

Fluid resists objects due to friction acts on the objects that are moving through fluid.

Frictional Resistance Law:

As per Darcy-Weisbach equation, the head loss due to friction is

\({h_f} = \frac{{fL{V^2}}}{{2gD}}\)

Frictional resistance also depends on velocity and temperature of flow. It is proportional to the surface area of contact for both laminar and turbulent flows. It is independent of the pressure for both laminar and turbulent flows.