Physics Study Guide/Print version - Wikibooks, open books for an open world

Universal constant of gravitation (G): This is a constant that is the same everywhere in the known universe and can be used to calculate gravitational attraction and acceleration due to gravity.
6.67x10^-11 N·m²/kg²

Mass one (m₁): One of two masses that are experiencing a mutual gravitational attraction. We can use this for the mass of the Earth (10²³ kg).

Mass two (m₂): One of two masses that are experiencing a mutual gravitational attraction. This symbol can represent the mass of an object on or close to earth.
Units: kilograms (kg)

Acceleration due to gravity (g): This is nearly constant near the earth's surface because the mass and radius of the earth are essentially constant. At extreme altitudes the value can vary slightly, but it varies more significantly with latitude. This is also equal to the value of the gravitational field caused by a body at a particular point in space
(9.8 m/s²)

Escape velocity (v_esc): The velocity necessary to completely escape the gravitational effects of a body.