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 24 September 2014

Last updated: 04 April 2007 1334 BST

Norfolk astronomer and Chairman of the Norwich Astronomical Society Mark Thompson tells you all about rocket science.
 A rocket at the NASA Space Centre Why and how do rockets fly? Local astronomer, Mark tells you the answer to rocket science.

If you're fascinated by rockets then here's our guide to building one of your own!

First, you need to think about how a rocket actually flies?

Imagine you are standing on a skateboard with your friend in front of you who is also standing on a skateboard.

Now, hold the palms of your hands against the palms of your friends hands and push.

 A rocket orbits Mars

As you push you will see how both you and your friend move away from each other.

The scientist Sir Isaac Newton called this the third law of motion.

He said that every action has an opposite and equal reaction.

Scientists later used this to make rockets work.

Inside most rockets is an empty tank. Different fuels are put inside this tank to mix with each other.

When they mix, they explode. The fuel tank has a hole in one end of it (the bottom end) and when the rocket fuel explodes, the explosion pushes (creates a force) against the sides of the tank.

Because the same amount of force goes against each side, nothing happens. At the same time, the explosion pushes against the top of the tank but not against the bottom because of the hole.

Because there is more force against the top end of the tank than the bottom the rocket reacts by moving in that direction.

The same thing happens with your rocket. The tablet starts to fizz when it is put inside the canister. With the lid on, the fizz creates lots of gas inside but it cannot get out.

Eventually there is so much gas that the lid of the canister (at the bottom of the rocket) gets blasted off and the rocket launches into the sky.

Try different amounts of water and different shapes to the rocket to see what happens. Have fun but be careful!

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