Modern Physics

# What is rotational balance?

A rotational balance is one that is generated when a body is having a rotation or twist. This phenomenon occurs when the torques exerted by the forces acting on the body are null.

That is, when the sum of all torques is equal to zero. These types of balances occur when the body does not undergo any variation during the rotational movement exerted on it.

The elements of rotation taken into account when expressing this phenomenon in mathematics are the force, represented by an “F”, the arm, represented by a “b” and the axis on which the rotation takes place.

## Balance classes

Like any phenomenon, there are several ways in which it can be produced and different characteristics that allow us to analyze certain types of processes. In the case of rotational equilibrium, there are three types of equilibrium to define it.

### Stable balance

The balance of a body is stable when that body is suspended and its center of gravity is below its suspension point.

On the other hand, when the body is supported, the stability of the balance will be noticed when the vertical that crosses the center of gravity is inside the base of the suspension.

### Unstable balance

The balance of a body is stable when it is suspended and its center of gravity is above its suspension point.

Likewise, when the body is supported, the stability of the scale will be noticed when the vertical that crosses the center of gravity passes through the limit of the base of the suspension.

### Indifferent balance

The balance of a body is stable when the body is suspended and its center of gravity coincides with the two suspension points.

On the other hand, when the body is supported, the stability of the balance will be noticed when the vertical that crosses the center of gravity always passes through the base of the suspension.

## Rotational balance factors

To present a rotational balance, it is necessary to have certain factors:

### Moment of force

The moment of force is a magnitude reached thanks to the cross product of the position vector where the force is applied by the force vector. This factor is also known as Torque, by the name in English torque.

### Pair of forces

A pair of forces is a system created with two parallel forces that have the same strength but are in the opposite direction. When applying said force, a rotational movement is generated.

### Gravity center

The center of gravity is considered to be the point of application of the union of all gravity forces acting on a body.

This center of gravity does not necessarily correspond to a material point and can be said to be the point at which the forces exerted by gravity are nil.

### Static balance

Static equilibrium is one that occurs when all the forces acting on a body are balanced. This means that this is what happens when a body is completely immobile and stable.

### Vectors

Vectors are a magnitude divided into magnitude and direction.