Question 1

How does pressure change with altitude?

Accepted Answer

Pressure drops ~12% per 1000m. Sea level: 1013 hPa. 3000m (10,000 ft): ~700 hPa. Everest summit: ~330 hPa.

Question 2

What is the barometric formula?

Accepted Answer

P = P₀ × e^(-Mgh/RT). Pressure decreases exponentially with altitude. Temperature affects the rate of decrease.

Question 3

What pressure units do different industries use?

Accepted Answer

PSI in US/UK automotive and HVAC. Bar/kPa in European engineering. mmHg/torr in medicine. Atmospheres in diving and altitude.

Question 4

Is gauge pressure different from absolute pressure?

Accepted Answer

Yes! Gauge pressure reads 0 at atmospheric pressure. Absolute pressure adds atmospheric (~14.7 psi). Vacuum gauge shows negative gauge pressure.

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