What is Centre of Gravity & where to find it in some regular objects easily?

In this post, we’ll first discuss what the Centre of Gravity is. And then we’ll quickly list down where to find the centre of gravity in some regular objects easily.

In simple words, the centre of gravity of a body is the point where the whole weight of the body can be considered to act.

The centre of gravity of a body may even lie outside the actual material of the body. For example, the centre of gravity of a ring lies at its centre, which is outside its material.

Centre of gravity of a rigid body – understanding in details with diagram

Consider a rigid body. It consists of a number of particles and these particles are attracted towards the earth due to gravity.

The forces acting on the particles are F1, F2, F3, etc. These forces act downwards along parallel lines. (Actually, these forces denote the weight components contributed by the particles.) These parallel forces can be replaced by a single force whose effect is the same as the combination.

This single force is the resultant of all the downwards forces. The resultant force acts at a particular point. This point can be assumed as the point where the whole weight, W of the body acts. This point is known as centre of gravity (C.G)

CG of a rigid body | centre of gravity

One more vital point: This C.G. point has another important characteristic. If moments (moment of force) of all the downward weight forces (from all particles) are calculated with respect to the C.G. of the object and then algebric sum of these moments is calculated then it will result into zero.

Define Centre of gravity | Definition

The Centre of Gravity (C.G.) of a body is the point about which the algebric sum of moments of weights of particles constituting the body is zero and the entire weight of the body is considered to act at this point.

Location of Centre of Gravity in some regular objects

This is a tabular-list of regular objects and the position of CG for each of them.

ObjectPosition of Centre of Gravity
Rodat the Midpoint of the rod
Circular Discat the Geometric center
solid or hollow sphereat the geometric center of the sphere
cylinderat the midpoint on the axis of the cylinder
circular ringat the center of the ring
triangular laminaat the point of intersection of the medians
parallelogram-shaped laminaat the point of intersection of the diagonals
rectangular laminaat the point of intersection of the diagonals
square laminaat the point of intersection of the diagonals
solid coneIt is at a height h/4 from the base, on its axis. (h = height of cone)
hollow coneIt is at a height h/3 from the base, on its axis. (h = height of cone)

FAQ

Where is the Centre of Gravity in a Rod?

It is at the midpoint of the rod.

Where is the Centre of Gravity in a Circular Disc?

It is at the geometric center.

Where is the Centre of Gravity in a solid or hollow sphere?

It is at the geometric centre of the sphere.

Where is the Centre of Gravity in a cylinder?

It is at the midpoint on the axis of the cylinder.

Where is the Centre of Gravity in a circular ring?

It is at the center of the ring.

Where is the Centre of Gravity in a triangular lamina?

It is at the point of intersection of the medians.

Where is the Centre of Gravity in a parallelogram-shaped lamina?

It is at the point of intersection of the diagonals.

Where is the Centre of Gravity in a rectangular lamina?

It is at the point of intersection of the diagonals.

Where is the Centre of Gravity in a square lamina?

It is at the point of intersection of the diagonals.

Where is the Centre of Gravity in a solid cone?

It is at a height h/4 from the base, on its axis. (h = height of cone)

Where is the Centre of Gravity in a hollow cone?

It is at a height h/3 from the base, on its axis. (h = height of cone)

Location of Centre of Gravity in some regular objects
Location of Centre of Gravity in some regular objects
What is Centre of Gravity & where to find it in some regular objects easily?
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