# Centrifugal Force: Definition, Unit, Formula, Example

A force is any push or pull that can cause an object to change its state of motion. It can make a stationary object start moving, stop a moving object, or even change the direction of a moving object. Forces are measured in Newtons (N) and have both a magnitude (strength) and a direction. Here, Centrifugal Force is also not a real force, but a pseudo force as it is a result of inertia. It describes an object’s tendency to fly outwards, away from the centre of a curved path. It also describes how an object reacts to changes in its state of motion or state of rest. In this blog, we will learn more about what is Centrifugal force along with its definition, the unit and daily examples.

Christian Huygens first identified this force as a force in 1659. He argued that it’s not a “real” force because objects moving straight continue to move straight. This is called “intrinsic inertia” because it protects objects from the force that moves them in a curve.

## What Is Centrifugal Force?

Centrifugal force is derived from the Latin terms “centrum” (center) and “fugere”( to flee) which literally means “centre-fleeing force”. It is an outward imaginary force which is felt by an object moving in a circular path and pointing away from the center of rotation known as centrifugal force. It is called a pseudo force or a fae force because it only seems to exist when there is a centripetal force. This force arises from the inertia of an object moving in a circular path. The centripetal force pulls towards the center of a circular path and is equal in size and direction to the centrifugal force. The axis of rotation runs parallel to the direction of the centrifugal force, which points away from it.

### Definition:

“ A pseudo force arising from a non-inertial frame of reference, perceived as acting outwards from the center of rotation”

This definition focuses on the core aspects:

1. Pseudo force: This force is not a real force acting on the object; it is a perceived sensation by the object.
2. Non-inertial frame: The feeling arises when you are in a rotating system, not in a state of uniform motion or rest.
3. Inertia: The object’s natural tendency to resist changes in motion (continuing in a straight line) creates the outward feeling.
4. Outward perception: It feels like a force pushing us outwards during circular motion.

Also Read – Difference Between Torque and Force

## How to Calculate Centrifugal Force?

Even though we cannot calculate the centrifugal force itself, by calculating the centripetal force, we can understand the magnitude of the perceived outward force based on inertia.

Here,

m  = Mass of the object.

v = Velocity of the object.

r = Radius of the object.

“-” = the minus sign representing the force as oppositive.

### Unit of Centrifugal Force

The unit of the force is kgms−2 or newton. Newton (N), Since Newton (N) is the unit of force in the International System of Units (SI), and it represents the product of mass (kg) and acceleration (m/s²), it perfectly fits the calculation for centripetal force. However, centrifugal force does not exist when measuring in the standard frame of reference; it only exists when measuring in the rotation frame of reference. Hence, it also has the same unit.

Also Read – Non-Contact Force: Types, Examples & More

## Is Centrifugal Force Real or Hypothetical?

The centrifugal force is considered hypothetical or pseudo because, as stated in the definition, it only appears to exist when a centripetal force is present. An example that can help us understand this is the movement of a passenger vehicle and its wheels. When the car is in motion, the centripetal force acts on all sections of the car, causing the occupants to feel a force pushing them towards the seat’s edge and the door. This force is perceived as centrifugal, related to the acceleration, but according to Newton’s second law of motion, it is not considered a genuine force.

## Relative Centrifugal Force

Relative Centrifugal Force (RCF) is a term used to describe a specific situation in which the radial force produced by the spinning rotor is close to the Earth’s per” g” (the acceleration due to gravity) force applied to the particles.

RCF is defined as the exponential form of the rotational speed, which is defined as the number of minute revolutions. The centrifugal force is determined by two factors. The first is the distance from the rotation axis and the second is the rotational speed. Double the rotational speed and the centrifugal force increases fourfold.

## Calculating RCF

RCF is a unitless quantity, often expressed as a multiple of “g” (the acceleration due to gravity). Here’s the formula:

RCF = (r * ω^2) / g

where:

• r is the radius of the rotor (distance from the center of rotation) in centimetres (cm)
• ω (omega) is the angular velocity of the rotor in radians per second (rad/s)
• g is the acceleration due to gravity (approximately 9.81 m/s²)

Using RCF:

By calculating the RCF for a specific centrifuge run, researchers can:

• Compare the separation effectiveness of different centrifuge settings.
• Compare results from different labs using similar centrifuges.
• Determine the appropriate RCF needed for a specific separation task.

## Example of Centrifugal Force

Some examples of this force are –

1. Riding a Ferris Wheel: At the top of the Ferris wheel, you might feel like you are being pushed outwards due to inertia. This outward sensation is centrifugal force, while gravity (a real force) pulls you downwards.
1. Blood in a Centrifuge: In a medical centrifuge, a centripetal force pushes blood outwards, separating heavier components (red blood cells) from lighter components (plasma) based on their different inertia. There is no true force acting on the blood itself.
1. Whipping Cream: As you whip cream, the circular motion creates a perceived outward force on the cream. This helps incorporate air bubbles, making the cream lighter and fluffier.
1. Oil Extraction: Centrifuges are used in oil extraction to separate oil from water or other liquids. The perceived centrifugal force on the components helps separate them based on their differing densities.
1. Balance in Bicycles: Leaning into a turn creates a centripetal force that keeps the bicycle from tipping over. This inward force creates the sensation of being pushed outwards due to inertia, similar to the feeling of a car taking a turn.

## FAQs

What is centrifugal force in simple words?

The centrifugal force is the force that causes a circular object to move away from its center. For example, if a propeller blade breaks at the root, it will fly off. The centrifugal force acts on a rotating object because it is the force that moves the object away from its axis of rotation.

Why is it called centrifugal?

The word “centrifugal” comes from the Latin “centrum” meaning “center,” and “fugere” which means “to flee,” so “centrifera” literally means “fleeing.” Physicists studied centrifugal force as early as 1629. In 1687, Sir Isaac Newton used the term in its Latin form vis centrifuga.

Is gravity a centrifugal force?

Gravity and centrifugal force are not the same. Gravitation works in opposite directions to centrifugal forces. Gravitation pulls the object towards the center of the Earth. Centrifugal force moves outward in a radial direction, trying to push the object out of the way.

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