At what altitude does the atmospheric pressure drop to about 70 % of its sea‑level value? Assume the pressure falls by 100 hPa per 1 km rise and sea‑level pressure is 1013 hPa.
Answer
about 3 km
The correct answer is about 3 km — Hence the pressure is 70 % of sea‑level value at roughly 3 km altitude.
Step-by-step solution
- 1. Calculate 70 % of 1013 hPa: .
- 2. Difference in pressure: .
- 3. With a drop of 100 hPa per km, altitude = .
- 4. Round to the nearest whole number: about 3 km.
- Hence the pressure is 70 % of sea‑level value at roughly 3 km altitude.
Common mistake: Assuming a linear drop without computing the percentage
Concept tested: Pressure variation with altitude
Published · How this solution was prepared and checked
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