Applications of Principle of Conservation of Momentum

Mixture of hydrogen and oxygen fuels burn in the combustion chamber.
Hot gases are expelled through the exhausts at very high speed .
The high-speed hot gas produce a high momentum backwards.
By conservation of momentum, an equal and opposite momentum is produced and acted on the rocket, pushing the rocket upwards.

Air is taken in from the front and is compressed by the compressor.
Fuel is injected and burnt with the compressed air in the combustion chamber.
The hot gas is forced through the engine to turn the turbine blade, which turns the compressor.
High-speed hot gases are ejected from the back with high momentum.
This produces an equal and opposite momentum to push the jet plane forward.