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.
When air is blown over the paper strip, the paper rises upward.
This happens because blowing air over the paper creates a region of low pressure above it. The higher atmospheric pressure below the paper pushes it upward.
This demonstrates that high-speed winds are accompanied by reduced air pressure, and air moves from high-pressure to low-pressure regions.
The faster the air is blown, the more the paper rises, confirming the relationship between air speed and pressure reduction.
Explanation
This activity demonstrates the principle explained in Section 6.4: 'high speed winds are accompanied by a reduced air pressure.' Similar to Activity 6.6 with balloons moving together, the paper rises because of the pressure difference created by the moving air.
Solution Steps
When air is blown over the paper strip, the paper rises upward
Blowing air over the paper creates a region of low pressure above it
Higher atmospheric pressure below the paper pushes it upward
High-speed winds are accompanied by reduced air pressure
Air moves from high-pressure to low-pressure regions
Faster air causes greater rise, confirming the air speed and pressure relationship