According to Newton’s first law of motion, a body in uniform motion will continue in its state of motion in a straight line unless acted upon by an external force. This law can be explained by the inertia of an object which resists any change in motion. In a circular motion, there is a continuous change in velocity as the direction changes continuously. The inertial force that tries to oppose this acceleration is called the centrifugal force. In this article, we will look at the definition, examples, and formula for centrifugal force.
Definition of centrifugal force
Centrifugal force is the outward pushing force on an object in a circular motion. It is not a real force and is directed away from the center. It is a result of the inertia of the object which resists the circular motion. The centrifugal force depends on the mass of the object, the velocity of the object, and the distance between the center and the object. The SI unit of this centrifugal force is Newton.
The direction of centrifugal force
Centrifugal force is directed away from the center towards the object and in the plane of rotation.
In the schematic above we can see a car in a circular motion. The car is continuously turning due to the centripetal acceleration. The centrifugal force of mv2/r tries to push the vehicle off the circle but is balanced by the centripetal force.
In the second schematic, a person is rotating a ball attached to a string. The tension force in the string provides the centripetal force which tries to pull the ball towards the center. This is balanced by the centrifugal force which pulls the ball away to ensure the ball remains in orbit.
Examples of centrifugal force
Image by Bessi from Pixabay
Examples of centrifugation forces are common in our daily lives but not very frequent as compared to other types of forces like gravitation or friction.
- The coating of photoresists on silicon wafers in the semiconductor industry uses a spin coater that spins at high speed to generate a centrifugal force which allows a uniform and controlled thickness of the coating material.
- Vehicles tend to skid off on tight turns due to the centrifugal force pushing them off the road.
- Gravitron/carousel rides in amusement parks use centrifugal force to give a thrill to the passengers.
- Centrifuge machines used in research laboratories use centrifugal force to separate fine micro or nanoparticle from liquids.
- Mud flying of a tire: The mud sticking onto the surface is thrown off tangentially due to the centrifugal force. The force of adhesion is very less, so the mud cannot hold on for long against the centrifugal force.
You can read our article on 10 examples of centrifugal force for more details.
Why doesn’t the earth spin-off due to centrifugal force?
Since the Earth is moving in a circular motion, it should ideally be thrown off orbit due to centrifugal force. But, the gravitational pull of the sun is strong enough to pull the Earth towards. In that case, the Earth should crash into the Sun. But, since the Earth is moving fast the centrifugal forces balances the centripetal force due to gravity.
If Earth rotates around its axis, then why are we no thrown off the Earth due to centrifugal force?
According to the laws of centrifugal force, an object in circular motion must experience centrifugal force with the formula mv2/r. Since we are in a circular motion due to the rotation of the Earth around its axis, there should be a centrifugal force working on us. But, in this scenario, the gravitational pull of the Earth with a formula G*m1m2/r2 is much greater compared to the centrifugal force. A scenario of we being thrown off is possible when the distance between us and the Earth increases or the Earth moves so fast that the centrifugal force is greater than gravitational pull. Also since the Earth is not a perfect sphere, the centrifugal force at the equator will be greater compared to the poles.
Inertia and centrifugal force
Centrifugal force is not a real force. Unlike centripetal force, there is no real force acting on the object like gravity, tension, etc. It is the inertia of the object that tries to maintain a straight path of motion against the circular motion. This inertia pulls the object off the circular path.
Centrifugal force formula
Centrifugal force is directly proportional to the mass of the object and the square of the velocity. It is inversely proportional to the square of the distance between the center and the object.
The above formula to calculate the centrifugal force. We can see from the formula how the velocity of the object is an important factor for generating centrifugal acceleration. If angular velocity is known then the centrifugal force can be calculated using the formula F = m*ω2*r, where ω is the angular velocity.
Industrial application of centrifugal force
Centrifugal pump: In a centrifugal pump, the rotational energy of a motor is used to convert centrifugal force into the hydrodynamic energy of the fluid. Reverse action is used in a hydrothermal plant where the potential energy of water is converted into rotational mechanical energy.
Centrifugal compressor: A centrifugal compressor consists of fans that are used to increase the pressure of a fluid.
Centrifugal partition chromatography: This is a type of chromatographic technique used to separate different constituents of a liquid dispersed in another liquid based on centrifugal force on the molecules. You can read this research article for more details.
Research on centrifugal force
Centrifugal force can be used in the electrospinning of nanofibers. In this article titled “research on the development of centrifugal spinning,” the authors study the factors that influence centrifugal spinning like rotation speed, evaporation, viscosity, etc.
Single-cell microscopy is a very tough technique, as it is very difficult to isolate a single cell for imaging. In this article, the authors use microfluidic traps based on the centrifugal force for the isolation of single cells for imaging.
See also
Banking of roads
Examples of centripetal force
Examples of centrifugal force
Differences between centripetal and centrifugal forces
Centripetal force
