A water rocket is a simple type of model rocket that uses water and air pressure to launch into the sky. It’s typically made from a plastic soda bottle, partially filled with water, and pressurized using a standard bicycle pump or air compressor. Once the pressure builds up and the rocket is released, the compressed air forces the water out of the bottle's nozzle at high speed and  pushing the rocket upward through the air. 

What Does This Law Means? 

Newton’s Third Law tells us that forces always come in pairs.
If one object pushes on another, the second object pushes back with equal strength but in the opposite direction.

Think of a water rocket sitting on the launch pad.

When you release it after pumping in air:

• The compressed air pushes the water downward and out of the nozzle.
  → This is the action force.

• In return, the rocket gets pushed upward into the sky.
  → This is the reaction force.