Rocket Propulsion

When the rocket engine burns fuel m so that it leaves the rocket with speed u, it carries momentum in one direction (to the left in this diagram). To conserve momentum, the rocket must carry momentum -- or gain additional momentum -- in the opposite direction (to the right in this diagram).

Conservation of momentum requires that

Sidebar or footnote:
Voyager 2 Approaching Uranus:

This artist's conception shows the final approach of the unmanned spacecraft Voyager 2 toward the planet Uranus on January 24, 1986. Voyager 2 discovered four new rings and ten new moons around Uranus. An interesting "sidebar" is that these rings of Uranus were discovered by a team of Astronomers led by Robert Millis, an Eastern Physics graduate. Dr Millis is now director of the Lowell Observoratory in Flagstaff AZ.

A Special Case

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(c) 2005, Doug Davis; all rights reserved