The Basic Principle: Newton's Third Law
A rocket works primarily on Newton's Third Law of Motion: for every action, there is an equal and opposite reaction. Inside the rocket engine, fuel and oxidizer are burned to produce hot, high-pressure gases. These gases are then expelled rapidly downwards through a nozzle.
Generating Thrust
The 'action' is the rocket expelling these hot gases at high velocity out of its exhaust nozzle. The 'reaction' is the thrust force that pushes the rocket upwards and forwards. The faster the gases are expelled and the greater their mass, the more thrust is generated.
Components for Propulsion
Rockets typically consist of a propulsion system (engine, fuel tanks for propellants like liquid hydrogen and oxygen, or solid propellant), a structural system, a payload, and guidance systems. The engine's combustion chamber creates the necessary pressure and temperature to accelerate the exhaust gases.
Application in Space Travel
This reaction principle allows rockets to accelerate and overcome gravity, propelling spacecraft into Earth orbit or beyond. Unlike airplanes that push against air, rockets propel themselves by pushing against the momentum of their own expelled exhaust gases, making them effective for propulsion even in the vacuum of space.