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Why is the speed of jet and rocket different?
Speed is a product of the difference between thrust and drag, so for this question we will look at how the two different engines produce thrust. A jet engine needs to compress the air that will mix with the fuel before it can be ignited. The method of compressing the air becomes ineffective once the speed of the air coming into the engine is about Mach 2.5, (2.5 times the speed of sound). In a rocket engine there is no incoming air that needs to be compressed, since there is already liquid oxidizer inside the rocket engine. This means rockets can travel MUCH faster than jets.