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Project
Hold a strip of paper, 18 cm long and 2 cm wide, between your thumb and forefinger so that it hangs freely. Predict what you will observe if you blow over the paper. Perform the activity now. Note down your observations and interpret your results.
Show sample answer
Key Points
When you blow over the top, the paper strip rises — fast air above it has lower pressure.
Key Points / Good Practices
- Predict first — many expect the strip to be pushed down, but it lifts up.
- Blow steadily across the top surface of the strip, not underneath it.
- The fast-moving air above lowers the pressure there.
- The higher pressure below then pushes the strip upward.
- This is the same idea as high-speed winds lowering air pressure.
Fast air over the strip lowers the pressure above it, so the strip rises.
