Try your hand at this Mini Miss Air Rocket Truck Race experiment.

What to do:

1. Cut a strip of Velcro that's about 15cm long.
2. Stick one side onto the top of the car or truck and stick the other lengthways down the bottle.
3. Take the lid off the bottle, fill it half full with water and screw the lid back on.
4. With the cone shaped adaptor attached on the pump, firmly push it into the opening of the bottle. It should be pushed in so hard that it's difficult to pull out. If it comes out easily, wrap a little tape around the adaptor (to make it a bit fatter) and try again (BUT DON'T TAPE THE ADAPTOR TO THE BOTTLE!).
5. With the adaptor now firmly in the bottle, stick the bottle onto the top of the truck using the Velcro, with the base of the bottle facing forwards. If your car falls over, try moving the bottle into slightly different positions until it doesn't.
6. Place your car-bottle rocket on a flat surface and make sure the path in front of it is clear.
7. Place your car-bottle rocket on a flat surface and make sure the path in front of it is clear.
8. Stand the pump to the side of the car-bottle rocket and pump...and pump...and pump! Keep on pumping. Don't slow down at all. You might want to get a friend to help.
9. If you pump fast enough, then eventually the adaptor and the water will be forced out backwards from the bottle and the car should be flung forwards.
10. If your bottle starts leaking the seal is not tight enough so wrap more tape around the adaptor and try again. If your rocket doesn't fire (no matter how hard you pump) then get an adult to carefully remove the adaptor from the bottle and try again.

What's happening here is all to do with Blast Lab's all time hero, Sir Isaac Newton. Newton was a genius, not only did he invent the cat flap he also came up with 3 rules about how things move around which he called his Laws of Motion.

It's his third law of motion that we use here. This law says 'for every action there's an equal and opposite reaction'. Basically, this means that to make something go up there has to be something pushing down. And to make something move forwards there has to be something pushing backwards.

In our bottle, when the pressure is built up enough it forces the stopper out of the bottle backwards and this makes the bottle and the truck go in the opposite direction - forwards.