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www.GOALias.blogspot.comFix the strips at the centre, putting one over the other so that theymake a plus (+) sign. Now fix the cups at the ends of the strips. Colourthe outer surface of one cup with a marker or a sketch pen. All the 4cups should face in the same direction.Push a pin through the centre of the strips and attach the strips andthe cups to the eraser of the pencil. Check that the strips rotate freelywhen you blow on the cups. Your anemometer is ready. Counting thenumber of rotations per minute will give you an estimate of the speed ofthe wind. To observe the changes in the wind speed, use it at differentplaces and different times of the day.If you do not have a pencil with attached eraser you can use the tip of aball pen. The only condition is that the strips should rotate freely.Remember that this anemometer will indicate only speed changes. Itwill not give you the actual wind speed.3. Collect articles and photographs from newspapers and magazines aboutstorms and cyclones. Make a story on the basis of what you learnt inthis chapter and the matter collected by you.4. Suppose you are a member of a committee, which is responsible forcreating development plan of a coastal state. Prepare a short speechindicating the measures to be taken to reduce the suffering of the peoplecaused by cyclones.5. Interview eyewitness to collect theactual experience of people affected bya cyclone.6. Take an aluminium tube about 15 cmlong and 1 to 1.5 cm in diameter. Cutslice of a medium-sized potato about2 cm thick. Insert the tube in the slice,press it, and rotate it 2–3 times.Remove the tube. You will find a pieceof potato fixed in the tube like apiston head. Repeat the same processwith the other end of the tube. Nowyou have the tube with both endsclosed by potato pieces with an aircolumn in between. Take a pencil withone end unsharpened. Place this endat one of the pieces of potato. Press itsuddenly to push the potato piece inthe tube. Observe what happens. Theactivity shows rather dramaticallyhow increased air pressure can push things.Fig. 8.20CAUTION: When you perform this activity, make sure that nobody isstanding in front of the tube.94SCIENCE