| Propulsion The basic principles of rocket propulsion stem from Newton's 3rd law of motion. The so-called law of action and reaction. A rocket propels itself by expelling material at high velocity, in the opposite direction to its motion. The material is usually a gas and the heat of a chemical reaction generally imparts the velocity. The heat builds pressure in a combustion chamber and is converted to exhaust velocity by the action of a properly designed nozzle. The principle is quite general and applies equally well to the motion of a simple garden sprinkler as it does to the powerful engines of the space shuttle.  |
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