Question

Define Drag coefficient of friction. On what factors does it depend?

Answer 1

Hint:In order to solve this question, we are going to firstly define the drag force, give the equation for drag force defining all the parameters included in the formula. Then, we are going to define the drag coefficient of friction. The factors on which the drag coefficient depends are also given.

Formula used:
The drag force is given by the formula:
$$D={\displaystyle \frac{1}{2}}C\rho A{v}^2$$
Here, $$C$$is the drag coefficient, $$\rho$$is the density of the fluid, $$v$$is the velocity of the body relative to the fluid and $$A$$is the projected area of the body.


Complete step-by-step solution:
The resistive force which is caused due to the motion of a body in a fluid such as water or air is known as the drag force. This force acts opposite to the motion of the body.
The drag force is given by the formula:
$$D={\displaystyle \frac{1}{2}}C\rho A{v}^2$$
Here, $$C$$is the drag coefficient, $$\rho$$is the density of the fluid, $$v$$is the velocity of the body relative to the fluid and $$A$$is the projected area of the body.
The drag coefficient is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water.
The drag coefficient depends on the following factors:
Mass of the flow going past the body immersed in the fluid.
Viscosity of the fluid
The compressibility of the fluid

Note:It is important to note that the drag coefficient of any object comprises the effects of the two basic contributors to fluid dynamic drag. These factors are the skin friction and form drag. The drag coefficient of a lifting airfoil or hydrofoil also includes the effects of lift-induced drag.