High School Physics + more

# Centripetal And Centrifugal Force

In this post, we will define centripetal force and centrifugal force, and find out how these two differ from each other. We will also go through some examples of these forces. In this discussion, we will also understand what centripetal acceleration is.

## Defining Centripetal Force

Centripetal Force (Fc) is the force that sustains the circular motion of a body by providing centripetal acceleration to it, and its direction is always towards the center of the circle.

This is the force that enables an object to continue its motion in a circular path. Centripetal force is a real force that acts on an object moving in a circular path. And this force acts towards the center of the circle.

The unit of centripetal force is Newton.

## Calculating Centripetal Force

The magnitude of the centripetal force can be calculated using this equation: Fc = mass x Centripetal Acceleration = mv2/r
where m = the mass of the object in motion, measured in kg
v = the linear orbital velocity or speed of the object in motion, measured in m/s
and, r = the radius of the circle, measured in m

## Centripetal Force Examples in Daily Life

We see many examples in daily life where the centripetal force is being applied. Here are 5 examples of centripetal force.

• a car or a bike taking a circular bend
• Washing machine operation
• Movement of the planets around the Sun
• the circular movement of the moon encircling the earth
• The electron orbits the nucleus in an atom

## What is Centrifugal Force?

Centrifugal force is a pseudo force or non-existing force in a circular motion which acts along the radius and is directed away from the center of the circle. The force does not exist when observations are made in an inertial frame of reference. It can only be experienced when observers are part of a rotating reference frame.

The centrifugal force’s unit is Newton.

## Calculating Centrifugal Force

To describe the pseudo centrifugal force, the formula of real centripetal force is used, just with a negative sign to denote that the direction of centrifugal force is opposite to that of the centripetal force.

Centrifugal force Fc‘= mv2/r

## Centrifugal Force Examples in Daily Life

When passengers travel in a bus and the bus takes a sharp turn, then the passengers feel thrust in the opposite direction. Here the bus is an example of a Rotating Frame of Reference and the passengers within that frame of reference feel a pseudo force, called centrifugal force. The road beside the bus is a static or inertial frame of reference. A person standing in that static frame will never reciprocate the presence of centrifugal force for that bus, to him the movement of the passengers is just because of directional inertia.

## Centripetal Force vs Centrifugal Force

Here is a list below to learn the detailed comparison between Centripetal and Centrifugal Force.

• The direction of the Centripetal Force is always towards the center of the circle. But, the direction of centrifugal force is directed away from the center of the circle.
• Centripetal force is a real force that acts on an object moving in a circular path. This is the force that enables an object to continue its motion in a circular path. Centrifugal Force is a pseudo force, it’s not a real force.
• Centripetal force evolves due to the mutual interaction of objects or masses. Centrifugal force is felt only within a Rotating Frame of Reference but doesn’t exist in reality.

## Defining Centripetal Acceleration

Centripetal acceleration is the acceleration provided by the centripetal force.
Acceleration in circular motion is referred to as centripetal acceleration (a). It is found that this acceleration is related to the orbital speed of the (uniform) circular motion and its direction is always towards the center of the circle.

The magnitude of the centripetal acceleration can be expressed as a = v2/r,
where v = the linear orbital velocity or speed of the object in motion, measured in m/s, and, r = the radius of the circle, measured in meters

What is centripetal force?

Centripetal Force (Fc) is the force that sustains the circular motion of a body by providing centripetal acceleration to it, and its direction is always towards the center of the circle.

Give examples of centripetal force.

The movement of the planets around the Sun and the circular movement of the moon encircling the earth are examples of centripetal force.

Does centripetal force increase with speed?

Yes! The formula for centripetal force is given by mv2/R. This means as the speed (orbital speed) of the particle increases, the centripetal force experienced by it also rises.

Does centripetal force increase with radius?

No! The expression for centripetal force is given by mv2/R. This suggests as the radius of the turn of the particle increases, the centripetal force experienced by it decreases.

Compare centrifugal force and centripetal force.

The direction of the Centripetal Force is always towards the center of the circle. But, the direction of centrifugal force is directed away from the center of the circle. Centripetal force is a real force that acts on an object moving in a circular path. But, Centrifugal Force is a pseudo force. Centripetal force evolves due to the mutual interaction of objects or masses. Centrifugal force is felt only within a Rotating Frame of Reference but doesn’t exist in reality.

What is Centripetal Acceleration?

Centripetal acceleration is the acceleration provided by the centripetal force. Acceleration in circular motion is referred to as centripetal acceleration.