What is a gravitational field?

We explain what gravitational fields are and how their intensity is measured. Examples of gravitational field.

1. What is a gravitational field?

Gravitational field or gravitational field is called the set of forces that represent, in physics , what we commonly call as force of gravity : one of the four fundamental forces of the universe , which tends to attract the masses of matter to each other.

According to the logic of gravitational fields, the presence of a body of mass M will subject the space around it to gravitational forces , altering the properties (the trajectory, for example) of everything around.

In fact, if another body of mass m approaches the gravitational field of M, we will notice that its movement is altered by the force of gravity . And, according to the theory of relativity, even time itself would be affected by these forces, distorting it and giving rise to singularities such as black holes, astronomical objects whose gravitational fields are so strong that not even light manages to escape them.

The gravitational fields were for many years of an eminently theoretical nature , understood by classical (Newtonian) physics as a vector field, and by relativistic physics as a second-order tensor field, but the discovery in 2016 of gravitational waves by LIGO experiment scientists seem to shed new lights on this matter.

2. Gravitational Field Intensity

The intensity of the gravitational fields or, what is the same, the acceleration of gravity (or simply gravity) is represented in classical physics by the symbol g and as a vector field, that is, of lines endowed with meaning and direction .

It is commonly defined as the force per unit of mass that a particular particle will experience in the presence of a mass distribution. It is usually expressed in Newtons per kilogram (N / kg).

The formula for its calculation, then, would be:

g = lim _{m → 0} F / m, where m would be a test mass and F the gravitational force acting on it.

3. Gravitational potential

The gravitational potential of a gravitational field is, in Newtonian mechanics, a scalar magnitude that is measured in joules per kilogram (J / kg) , and that is defined as the amount of work per unit of mass needed to transport a body to a constant speed from infinity to a certain point of the gravitational field in question.

Gravitational potential is calculated based on the following formula:

V = – GM / r, where V is the gravitational potential, G is the universal gravitation constant and r the distance from the determined point of the gravitational field to which the mass M moves.

4. Examples of gravitational field

A perfect example of the gravitational field is the solar, that is, the one presented by our planetary system , in which the planets orbit around the sun , attracted by the gravitational forces of their mass.

Another possible example is the earth’s gravitational field , our own planet and which we can feel every time we drop an object to the ground . In comparison with our size, the mass of the Earth 5974 x 10 ²⁴ kg it is so massive that its field properties are difficult to pinpoint the naked eye.

However, it is estimated that the earth’s gravity is more or less than 9.8 N / kg, that is, an acceleration of 9.8m / s. This value can oscillate minimally depending on the geographical location, but in general terms it presents that value and tends towards the very center of the Earth.

Also, the gravitational field will be more intense in the immediate vicinity of the earth’s surface, than in the outer layers of the atmosphere.