Drag Force-Definition, Formula, Types, And Examples

Drag force is the force exerted on a body that is moving through a fluid. When a body moves through a fluid, it experiences drag force due to friction between the surface of the object and the surrounding liquid.

What is Drag force?

If we consider a sphere moving through the water, then the drag force acting on the sphere is equal to the weight of the sphere multiplied by its velocity. In general, if an object’s mass is much larger than the density of the fluid, then the drag force is proportional to the square of the velocity. However, if the mass is comparable to or smaller than the density of the liquid, then the drag force becomes independent of the velocity.

Drag force is the force exerted on a body moving through a fluid. When a body moves through a fluid, friction between the surface of the body and the surrounding fluid causes the body to experience a drag force. In fluids, the drag force is proportional to the velocity of the object relative to the fluid.

Drag Force Formula

The drag force is defined as

F=6πμvr

where μ is the dynamic viscosity of the fluid, v is the velocity of the object and r is the radius of the object.

In liquids, the drag force is directly proportional to the square root of the velocity.

For example, if we have a sphere moving at a speed of 1 meter per second through water, then the drag force would be equal to 0.5 N. If we double the speed of the sphere to 2 meters per second, then the drag force increases to 1N

Drag forces can cause problems for objects moving through fluids. For example, if a boat is traveling through water at a constant speed of 5 meters per second, then its drag force is equal to 10 Newtons. However, if the boat were to increase its speed to 20 meters per second, then its drag force would increase to 50 Newtons.

Drag forces can also cause problems for objects moving in the air. For example, if an airplane is flying at a constant altitude of 30 kilometers above sea level, then its drag force would be equal in magnitude to the weight of the plane. However, if the plane were to fly higher than 30 kilometers, then its drag force could exceed the weight of the plane causing the plane to lose altitude.

Drag Force Types

There are many types of drag force.

Parasite Drag

Every force that can be used to slow a vehicle down is referred to as parasite drag.

Skin Drag Force

Air exposure to the craft’s outer surface causes skin friction drag, an air resistance generated on the aircraft.

Lift Induced Drag

Lift-inducing drag is the result of the normal lift mechanism. The lift Induced drag is generated by the wing of the aircraft.

Interference Drag

The interference drag is created due to the different speeds of the different airflows. The drag force is generated by the interference of various aircraft components It is due to the lack of similar airflow around the wing and the fuselage.

Wave Drag

This drag force can only be used for supersonic scenarios. It is a type of drag force produced from non-canceling static pressure variables to either side of a shock wave striking on the outer surface of the object, from which the wave is generated.

Drag Force Example

These are a few examples of drag force

• Force acting on a paraglider
• Force on freely falling bodies
• Force on Floating objects
• Force acting on a parachuter
• Force on a moving vehicles