Explain how you would manipulate these materials to make a tornado.
· Two empty one-liter soft drink bottles, rinsed out, labels removed
· Rubber or steel washer that has the same diameter as the mouth of the bottles, containing a small hole
· Roll of strong electrical or duct tape
· Water

Using the said items, you can make a 'Tornado in a bottle' - which is actually a vortex (like a whirlpool or a mass of rapidly whirling fluids). This experiment could be a good science fair project idea for kids.

Explanation:

Procedure:

1. Take one of the bottles and fill it up about 3/4 with water, tightening the rubber or steel washer on it.

2. Place the other bottle upside down on the washer and use the duct tape or electrical roll to attach them together.

3. Turn the contraption over so that the bottle with the water in it is on the top.

4. Shake the bottle round and round to make the water start swirling.

5. To see the vortex more clearly, add some food coloring to the water before swirling.

How it happens:

In the vortex formed between the two bottles, the water towards the outside tends to move at a greater speed than the water on the inside to keep up. This is a good explanation of how even though the eye of the hurricane is calm, strong winds can be felt at considerable distances from a tornado too.

b is the answer.   i sat on the lumpy sofa, totally exhausted, with a bad taste in my mouth, wondering what i should do next.  

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