A rocket engine functions by converting stored chemical energy into kinetic energy via the rapid expulsion of mass. The process begins with the controlled combustion of propellants—a combination of fuel and an oxidizer—within a combustion chamber. This reaction generates extremely hot, high-pressure gas. The gas is then directed through a nozzle, which expands and accelerates the flow significantly, creating a high-velocity exhaust stream. According to the principle of conservation of momentum, the reaction force exerted by the expelled gas in one direction results in a reaction thrust that propels the engine and attached vehicle in the opposite direction. The efficiency and performance of the engine are governed by factors such as chamber pressure, exhaust velocity, and the engine's overall thrust-to-weight ratio.