Gravitational field

A mass $M$ is said to create a gravitational field around it, so if some mass is placed at a point near $M$, it feels the field in the form of a gravitational force.

We define the field strength as:

The gravitational field strength at a certain point is the gravitational force per unit mass experienced by a small point mass $m$ placed at that point; measured in $\frac{N}{kg},\frac{m}{s^2}$.

It’s a vector quantity whose direction is given by the direction of the force a point mass would experience. Borrowing from Newton’s law of gravitation:

$$g=\frac{F}{m}=G\frac{M}{r^2}$$

See also

• Electric field
• Magnetic field