What it shows
A windsock points away from the wind and lifts higher as the wind gets stronger. It is used at airports and can be compared with a Beaufort chart.
The science
Wind pushes air into the wide mouth of the sock, filling it. The narrow end lets air flow out, and the sock turns to line up with the wind. In a light breeze it droops, and in a strong wind it stands almost straight. The angle of the sock shows the wind speed, and the direction it points away from is the direction the wind blows from.
Materials
Cost: free. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- An old cotton cloth, about 60 cm by 40 cm
- Strong wire or a cut plastic bottle ring
- Thread and needle or stapler
- A stick or pole
- Orange and white paint or cloth strips
- A string
Safety
For this project: An adult must bend and cut the wire. Do not climb to fix it high up.
Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.
All the safety rulesStep by step
8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.
Fold the cloth into a cone shape with an open mouth about 25 cm wide and a narrow end about 8 cm.
Stitch or staple the seam.
Fix the wire or bottle ring around the mouth as a frame.
Paint alternate stripes of orange and white.
Tie three strings from the ring to a swivel at the top of the pole.
Fix the pole in the open.
Note the angle of the sock from the pole several times a day.
Compare with a table: hanging for calm, half up for a breeze, level for strong wind.
What you should see
The windsock points away from the wind and the tilt changes with its speed.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
1Which way does the windsock point?
Away from the wind, the way it is blowing.
2What does a straight sock mean?
A strong wind.
3Where are windsocks used?
At airports and helipads.
4Why is the end narrow?
So the sock fills and the air escapes slowly.
Take it further
Record direction and strength for a week and draw a wind rose.
Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.
Free ebooks for this project
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