Answer to Question #141525 in Mechanics | Relativity for Keleko Pierre Michelle

Question

A rocket is propelled by the emission of hot gases. It may be stated that both the rocket and the emitted hot gases each gain kinetic energy and momentum during the firing of the rocket. Discuss the significance of this statement in relation to the laws of conservation of energy and momentum, explaining the essential difference between these two quantities.

Answer 1

Rockets are governed by Newton's Laws of Motion. Newton's Third Law states that "every action has an equal and opposite reaction". In a rocket, burning fuel creates a push on the front of the rocket pushing it forward. This creates an equal and opposite push on the exhaust gas backward. The rocket and the hot gases thus gain momentum and hence kinetic energy in opposite directions. In the process, both energy and momentum are conserved.