Physics Module 7 - Gravitation

Newton’s third law

states that all forces come in pairs and that the two forces in a pair act on different objects, are equal in strength, and are opposite in direction

Kepler’s first law

states that the paths of the planets are ellipses, with the Sun at one focus

Kepler’s second law

states that an imaginary line from the Sun to a planet sweeps out equal areas in equal time intervals

Kepler’s third law

states that the square of the ratio of the periods of any two planets revolving about the Sun is equal to the cube of the ratio of their average distances from the Sun

gravitational force

the force of attraction between two objects that is proportional to the objects’ masses

law of universal gravitation

states that the gravitational force between any two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers

centripetal acceleration

the center-seeking acceleration of an object moving in a circle at a constant speed

inertial mass

a measure of the object’s resistance to any type of force

gravitational mass

a quantity that measures an object’s response to gravitational force