# What is the Difference Between Centroid and Centre of Gravity

The key difference between centroid and centre of gravity is that the centroid of a plane figure is the arithmetic mean position of all the points in the figure, whereas the centre of gravity of a material is a point that is useful for a summary description of gravitational interactions.

Usually, every object has a mass, and it weighs a certain amount due to the effect of gravitational force. The two terms, centroid and centre of gravity describe the physical properties regarding gravitational forces.

### CONTENTS

1. Overview and Key Difference
2. What is Centroid
3. What is Centre of Gravity
4. Centroid vs Centre of Gravity in Tabular Form
5. Summary – Centroid vs Centre of Gravity

## What is Centroid?

The centroid of a plane figure is the arithmetic mean position of all the points in the figure. In other words, it is the point at which we can perfectly balance a cutout of the shape on the tip of a pin. Therefore, it is the geometrical centre of a body. We can describe it as the centre of gravity of uniform density objects. We can denote the centroid of gravity as “c”. It is the point in a plane area at which the moment of area about any axis throughout that point is zero. The centroid of gravity is the measure of the amount of geometry.

Figure 01: Centroid of a Triangular Object

The centroid corresponds to the centre of gravity where the body is homogenous and has a constant gravity. It is the focal point of the vectors’ collection of the gravitational acceleration of all other material points in that object. When the object is homogenous, the centroid is equal to the centre of gravity of that object.

## What is Centre of Gravity?

The centre of gravity is the point where the total weight of an object is focused upon. At this point, the gravitation force acts on the object. We can denote the centre of gravity as “g”. We can give the centre of gravity as the average of all points that are weighted by local density or specific weight. We can describe this as a physical behavior of an object and a point at which all the weight of the object is acting on.

More importantly, the centre of gravity for a certain body can exist in a point that is outside the mass limit of the body. This depends on the shape of the object. When considering irregular geometric objects, the centre of gravity is located at the intersection of the gravity lines.

## What is the Difference Between Centroid and Centre of Gravity?

There are two terms known as centroid and centre of gravity, which describe the physical properties regarding gravitational forces. The key difference between centroid and centre of gravity is that the centroid of a plane figure is the arithmetic mean position of all the points in the figure, whereas the centre of gravity of a material is a point that is useful for a summary description of gravitational interactions. Moreover, a centroid is the geometric centre of an object while the centre of gravity is a point at which the weight of a body or a system acts on.

The following infographic lists the differences between centroid and centre of gravity in tabular form for side by side comparison.

## Summary – Centroid vs Centre of Gravity

Centroid and centre of gravity are two terms that describe physical properties regarding gravitational forces. The key difference between centroid and centre of gravity is that centroid of plane figure is the arithmetic mean position of all the points in the figure, whereas centre of gravity of a material is a point that is useful for a summary description of gravitational interactions.