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Einstein Year - a year celebrating physics - Bluffs
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Bluffs

Here are three tricks from our Physics to Go pack. We have prepared three explanations for how each trick works but only one of the explanations is the truth - the other two are bluffs.
See if you can work out which one is the truth - or you can use these explanations to play our 'Call my physics bluff' game. You can find out the correct answers by looking at the tricks section of the Physics to Go pack.



Trick 1. Alka Seltzer Rocket

See a demonstration of the Alka Seltzer Rocket
Explanation 1. The Alka Seltzer solution heats up the lid, which expands releasing the base of the canister which leaps into the air away from the heat.
Explanation 2. The Alka Seltzer releases carbon dioxide that builds up pressure and forces the lid off the canister.
Explanation 3. The plastic lid is magnetically repelled by the Alka Seltzer solution.



Trick 2. Balloon Kebabs

See a demonstration of the Balloon Kebab trick

Explanation 1. Wood fibres from the skewer bond to the rubber molecules, reinforcing the hole and preventing the balloon from bursting.
Explanation 2. The balloon has been inflated in such a way that the air pressure on the outside is equal to the air pressure on the inside.
Explanation 3. There is less surface tension at the two points where the skewer goes through the balloon rubber.



Trick 3. Waterproof Hanky

See a demonstration of the Waterproof Hanky
Explanation 1. The gaps in the weave of the hanky are too small to let the water molecules through.
Explanation 2. The water forms a membrane by surface tension. Air pressure then acts on this membrane with enough force to keep the water in the glass.
Explanation 3. Hankies are usually made from a unique waterproof material which is why they are useful for blowing noses.


System Requirements: You may need to download Shockwave Flash to view the demonstrations