Science

# Center of Mass Vs. Center of Gravity

The difference between the center of mass and the center of gravity are two concepts that come up frequently in the study of physics and often found in the study of dynamics particularly in physics. These are also concepts that are more confusing to each other, and generally, people use them interchangeably, which is wrong. This article will explain the difference between the center of mass and the center of gravity and allow readers to have a clearer understanding.

## Difference between center of gravity and center of mass

Content:

• Main difference: center of gravity and center of mass
• What is the center of the mass
• What is the center of gravity
• What is the Difference Between Center of Gravity and Center of Mass

## Main Difference: Center Of Gravity And Center Of Mass

The Center of gravity and center of mass are the two terms that come up frequently in the study of dynamics in physics. The main difference between the center of gravity and center of mass is that center of mass is defined as the “weighted average” position of mass in a body, while the center of gravity is defined as the point around which the sum of the torques due to the gravitational forces is 0. For bodies with uniform gravitational fields, the center of gravity and the center of mass is the same.

## What is The Center Of The Mass?

The center of mass is the point in the body or a system of particles where its mass appears to be concentrated. It is found by taking the weighted average position of the mass. The equations used in dynamics are often applicable to the center of mass. When the momentum of a particle system is calculated, the speed of the center of mass is used as the speed of the system.

Moreover, whenever external forces are applied to a system of many particles or a body, the body behaves as if the external forces are applied to the center of mass. . For example, if you throw a stick at an angle, it may rotate as it falls, however, its center of gravity would move in a parabolic path, as the equations of motion predicted.

For symmetrical objects of uniform density, the center of gravity is at the geometric center of the object.

## What is The Center Of Gravity?

The center of gravity is the point through which all of the body’s weight seems to act. The sum of the torques due to gravitational forces is approximately zero of the center of mass. A body can be balanced by applying a force through the center of gravity.

In addition, if a body is suspended, the center of gravity falls directly below the point of suspension. The center of gravity is also important for stability: a body would tip over if its center of gravity was not directly above its base.

Rocks carefully piled up on each other maintain their balance because they are positioned so that the stones’ center of gravity aligns along a single vertical line.

If a body is in a uniform gravitational field, then we can show that the center of gravity and the center of mass coincide. This is roughly the case for objects close to the Earth’s surface, whose dimensions are much smaller than the radius of the Earth. However, this is not the case for large objects in space.

For example, if you think of the moon as a roughly spherical object, its center of mass is quite close to the geometric center of the “sphere”. However, the side of the moon closest to Earth experiences a stronger gravitational pull compared to the side farther away. Therefore, the center of gravity is located not at the geometric center, but on the side closest to the Earth.

## What is the Difference Between Center of Gravity and Center of Mass?

The center of mass of a rigid body is also called the center of gravity. However, this is true only in circumstances where the gravitational forces are uniform. Since the Earth’s gravitational force is considered uniform everywhere, the center of mass and center of gravity are effectively equal. Center of gravity is defined as the average location of an object’s weight.

In the case of Earth, since the gravitational pull is the same everywhere, each element of mass would weigh the same, so that the center of gravity is identical to the center of mass. However, in a non-uniform gravitational field, the center of gravity is not the same as the center of mass. The center of mass is a fixed property, which is the average location of the body’s mass. It has nothing to do with gravity.

### Definition

The center of mass is the weighted average position of mass in a body or system of particles.

The Center of gravity is the point in a body where the net torque due to gravitational forces is zero.

### Dependence on gravitational fields

The center of mass does not change as the strength of the gravitational field across a body varies.

Center of gravity can change as the strength of the gravitational field across a body varies.

### Position in a symmetrical body with uniform density

The center of mass is at the geometric center in a symmetrical body of uniform density.

Center of gravity is at the geometric center in a symmetrical body of uniform density, only if the body is in a uniform gravitational field.

### Use in dynamics

The center of mass is considered to be the point at which all the masses of a body or system of particles appear to be concentrated.

Center of gravity is considered to be the point at which a body’s weight appears to act.

## More on Center of Mass vs. Center of Gravity

• The center of mass and center of gravity are often considered to be one of the studies of physics due to the uniform gravitational pull of the earth.

• However, in non-uniform gravitational fields, the center of mass is far from the center of gravity

• This fact is used by designers to manufacture cars with a very low center of mass, in order to provide better balance.