Lectures on Physics has been derived from Benjamin Crowell's Light and Matter series of free introductory textbooks on physics. See the editorial for more information....

Pluto and Charon

i / Example 3. Computerenhanced images of Pluto and Charon, taken by the Hubble Space Telescope.

Pluto's moon Charon is unusually large considering Pluto's size, giving them the character of a double planet. Their masses are 1.251022 and 1.9x1921 kg, and their average distance from one another is 1.96104 km. What is the gravitational force between them?

If we want to use the value of G expressed in SI (meter-kilogramsecond) units, we first have to convert the distance to 1.96 107 m.

The force is

Last Update: 2009-06-21