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Science corner

Sophie Duncan shows how to lift off with Newton

Newton's three laws of motion can form the basis of some fun science investigations. This week we explore his second law, which states that for every action there is an equal and opposite reaction. This experiment needs to be handled carefully as it is a little explosive.

Each student will need a film canister and a piece of paper. First, create a rocket shape using the paper. You could create a simple template, but most students prefer to design their own. Remove the canister's lid and wrap the paper around the canister, attaching it firmly.

The lidless end of the canister is at the bottom of the rocket. Add a nose and fins and decorate your rocket. Create a launch station, using half of a paper-towel inner tube as the launch pad.

Wear protective eye gear, and ensure that no one stands in the way of the rocket. For fuel, fill the film canister a third full of water and add half an antacid tablet.

Quickly replace the lid and put the rocket into the launcher, ensuring the canister is upside-down, with the lid on the bottom.

Stand well back and wait. It can take a few moments to launch, but eventually your rocket will shoot into the air dramatically.

The antacid tablet produces carbon dioxide gas when mixed with water. The carbon dioxide has nowhere to go, and the pressure inside the canister increases. Eventually the gas and water escape from the bottom of the rocket. This action causes an equal and opposite reaction and the rocket launches into the air.

This is a very similar principle to a normal rocket. For more investigations, try to measure how high the rockets fly, and see how you can improve their performance.

Sophie Duncan is project manager for science at the BBC www.bbc.co.ukscience

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