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Q & A: what pushes rockets

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Most recent answer: 04/14/2010
Q:
how do rockets move in space if there is nothing for teh gasses pushing out of the rocket to push against?
- martha
columbus georgia
A:
That's an often-asked question. You're right that the rocket must push something backward in order to accelerate forward. It's the gases themselves that the rocket pushes on. They go backwards, the rocket accelerates forward.The rocket's velocity can increase without violating conservation of momentum, because the gases gain backward momentum while the rocket gains forward momentum, adding up to no net change.

Once all the fuel is burned, the rocket just keeps going, as would anything else. You only need a force to accelerate something, not to keep it moving.

Mike W.

(published on 04/14/2010)

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