13.1.1—A gravitational field is an example of a field of force and define

A gravitational field is a region in which a mass experiences a force due to gravity; field strength g is force per unit mass.

Use the field as a property of the source distribution, then calculate the force on a test mass with F=mg.

Near Earth, g≈9.8 N kg⁻¹ means a 2 kg mass experiences about 19.6 N downward.

The field exists even when no test mass is present, and g is not universally constant everywhere.