Transcript Aquajet science By: Rick Newlands What’s an aquajet? • ‘Aqua’ means ‘water’. • An aquajet is a rocket that uses water. • You fill a.

Aquajet science
By: Rick Newlands
What’s an aquajet?
• ‘Aqua’ means ‘water’.
• An aquajet is a rocket that uses water.
• You fill a plastic bottle 1/3rd full of water,
then pump the bottle up with air.
• Then you let it go and it flies away!
• The water jets out of the bottle.
Paisley Rocketeer’s Society
Mr Stewart of the Paisley
Rocketeers taught us how to
make aquajets.
Forces
• Aquajets work by making a force.
• A force is a push or pull that tries to move something.
• In Star Wars, the 'force' is a mysterious power that Jedi
Knights have to push, pull, or throw things without
touching them.
• If your family loses their housekeys and can't get into the
house, dad may have to 'force' the front door, which means
kicking the door down.
• A 'force 10' wind is a howling gale with the strength to
blow the roof off a house.
The push-back force
• Imagine that you and a friend are both on skateboards,
and you push your friend away …
• You’ll find that you get pushed backwards yourself!
The reaction force
• The famous scientist Isaac Newton called the push force that you make
the action force. The push-back force that then magically occurs and
pushes you backwards, he called the reaction force.
• So forces always come in pairs: the action and the reaction.
• With rockets, the reaction force is called thrust.
Aquajet rockets
• Aquajet rockets work by pushing water away from them. The pushing
away is the action force.
• The reaction force that then occurs pushes on the front of the aquajet,
moving it forwards.
• Notice that all the pushing goes on inside the rocket, so it doesn’t
matter what’s outside. It could be empty outer Space outside but the
rocket will still work.
How it works: squashed air
• Air can be squashed just like squashing a big spring.
• To make the action and reaction forces happen to the aquajet, then first
we’ve got to fill the aquajet bottle with lots of very squashed air.
• As the air gets larger, it gets squashed!
Launching the aquajet
• Now that we’ve squashed the poor old air, we can then open the
aquajet bottle and the air will un-squash and push the water out at high
speed.
• So it’s the squashed air that makes the action force.
• Launch the aquajet!
• The air pushes on the water, but also pushes on the front of the bottle,
which moves the aquajet forwards.
Big rockets
• Big rockets burn fuel to keep making hot, squashed gas.
• Instead of pushing water away, the new hot gas pushes away old hot
gas that was made a few moments earlier. This is the action force.
• The new gas also pushes on the front of the bottle: this is the reaction
force that pushes the rocket forwards.
Finish the aquajet
• We add a nosecone to the front of the aquajet to let it cut through the
air more easily, so that it flies further.
• Then we add some weight to the nose, and also add fins at the back.
These keep the aquajet flying nose-first like a dart. (Without the fins
and noseweight, the aquajet would just tumble through the air and
wouldn’t fly very far.)
• We make the nosecone soft and squashy just in case the aquajet lands
on your head!