How does the rocket race car works (Procedure)

How it works:
As you pump air into the bottle, pressure inside the bottle gets higher and higher. The pressure pushed on the inside of the bung and eventually gets high enough to push the bung out of the bottle's neck. Then the air pressure pushes water out of the bottle at high speed. Because the bottle pushes one way, and the water pushes the bottle the other way( this is a action reaction).

How do operate it:
1.) fit the needle valve into a foot pump or bicycle pump.
2.) Half fill the plastic bottle with water from tap.
3.) Push the bung into the neck of the bottle.
4.) Place the rocket race car on the ground outdoors, where it will have space to zoom forwards. Launch on a smooth outdoor surface.
5.) Start pumping air into the bottle. The air pressure in the bottle will rise until the pressure will push the cork out, a jet of water will shoot from the bottle.