Centrifugal Force: Learn its Definition, Formula, Unit, Examples, Applications, Numericals

Centrifugal force is a fictitious force that appears to push an object away from the center of the circular path due to the object's inertia. Physics is all about studying day-to-day phenomena. Let’s discuss one of our childhood phenomena of whirling a ball tied tight with string. When you pull a ball in order to make it exhibit circular motion, you exert some force on the system towards the centre. In return, as a consequence of Newton’s third law, the ball also exerts some forces on your hand in an outward direction that will be similar to the applied force from your side. We call this outward force, centrifugal force.

In this article, we are going to study more about centrifugal forces and how these forces work.

What is Centrifugal Force?

The term Centrifugal, means ‘away or out from the centre’. Centrifugal force is a pseudo force arising due to the body’s tendency to maintain its state, which seems to act on the system moving in a circular path and is directed radially away from the centre about which the system was rotating. As mentioned, it is a pseudo force and thus does not exist in reality.

Unit of Centrifugal Force

Centrifugal force is also a special kind of force (pseudo force), thus its unit is similar to that of force. It is also a vector quality, having both directions and magnitude.

The S.I. unit of Force: Newton or Kilogram meter per second squared or .

Centrifugal Force Formula

The formula required to calculate the centrifugal force can be defined as the ratio of the product of mass and velocity squared to the radius of the path of rotation. It is also sometimes expressed as the product of mass, radial distance from the axis of rotation and square of angular velocity or omega (ω).

Centrifugal force can be calculated using the expression,

……(1)

Here,

= Centrifugal force

m = mass of the object

v = velocity of rotating object

r = radial distance of body from the axis of rotation

On multiplying and dividing by ‘r’ in RHS of Equation (1), we obtained,

…..(2)

Clearly, we know that, = (ω) = angular velocity

Substituting this value in equation (2) we obtained

This equation can also be used to calculate the centrifugal force given that angular velocity is provided.

Since centrifugal force is a kind of force, thus its dimensional Formula is similar to that of force,

Dimensional Formula =

Relative Centrifugal Force

Relative centrifugal force or also sometimes referred to as g-force is a measurement of gravitational force acting on the sample body during the process of centrifugation. This force is produced from the turning of the rotor which, in return as a reaction, applies this force outward on the centrifuge tube.

It is expressed as the multiple of Earth’s gravitational force field, g.

The Relative Centrifugal force or RCF is related to the Revolution per minute (RPM) which is the speed of rotating in a centrifuge, by the following expression,

Difference between Centripetal and Centrifugal force

The table below lists the difference between centrifugal and centripetal forces:

Parameters	Centrifugal force	Centripetal Force
Definition	Centrifugal force is a pseudo force arising due to the body’s tendency to maintain its state, which seems to act on the system moving in a circular path and is directed radially away from the centre about which the system was rotating	Centripetal force is defined as the force necessary to keep the body in a circular motion and directed radially inward towards the centre of rotation.
Frame of Reference	It can be observed from the non-inertia frame of reference.	It is observed from an inertia frame of reference
Nature	It is a pseudo force in nature	It is a real force in nature
Examples	Driving vehicles around the curve	Satellites orbiting around the planets.

Examples of Centrifugal Force

We usually come across various physical phenomena in our day-to-day life. But we rarely observe or know the working mechanism and principles of any. In this part, we are going to do the same. We are going to discuss some daily life examples based on the principle of centrifugal forces and their mechanism as well:

• The outward that acts on the passenger in the bus or in any vehicle while taking a turn is nothing but centrifugal force
• The children sitting in the merry go round experience an outward pull that is rotated around its vertical axis.
• When a bucket full of water is rotated vertically with some velocity, its water won’t come out. This is because of the fact that the weight of water gets balanced by the centrifugal force acting due to rotation.

Application of Centrifugal Force

The concept of centrifugal force is applied in various places to solve real-life problems.

• It helps in the invention of the centrifuge which is nowadays used to separate particles suspended freely in the fluid by spinning at a very high speed.
• It is used in the construction of roads to improve friction on the curves and avoid skidding.

Solved Examples on Centrifugal Force

Example 1: A car of mass 1000 kg is traveling around a circular track with a radius of 50 meters at a speed of 20 m/s. What is the centrifugal force acting on the car?

Solution. Given:

Mass= 1000 kg

Radius= 50 m

Velocity= 20 m/s

= 8,000 N.

Therefore, the centrifugal force acting on the car is 8000 N.

Example 2: A satellite of mass 1000 kg is orbiting the Earth at a radius of 6.38 × 10⁶ meters with a speed of 3.07 × 10⁴ m/s. What is the centrifugal force acting on the satellite?

Solution. Given:

Mass= 1000 kg

Radius= 6.38 × 10⁶ m

Velocity= 3.07 × 10⁴ m/s

= 5000 N

Therefore, the centrifugal force acting on the satellite is 5000 N.

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