PhysicsLAB: The Law of Universal Gravitation

The Law of Universal Gravitation states that every object in the universe attracts every other object in the universe with a force that has a magnitude which is directly proportional to the product of their masses and inversely proportional to the distance between their centers squared.

where

G is the gravitational constant, 6.67 x 10^-11 Nm²/kg²
M₁ is the mass of the first body in kg
M₂ is the mass of the second body in kg
R is the distance from the center of M₁ to the center of M₂

This is the first of several important inverse-square relationships that we will study: light intensity and electrostatic force are two others.

Let's practice this relationship by looking at a few examples.

Refer to the following information for the next four questions.

Given that the gravitational attraction between two objects of mass M that are located a distance r apart is called F.

	How would the force change between these two objects if the distance between them were to be doubled to 2r?

	How would the force change between these two objects if the distance between them were to be halved to ½r?

	How would the force change between these two objects if one object magically doubled in mass while the other object magically tripled in mass while the distance between them stayed the same, r?

	How would the force change between these two objects if one object magically doubled in mass, while the other object magically tripled in mass, and the distance between them doubled to 2r?