Atmospheric pressure is half its sea-level value at an altitude of about
A) 1 km 3300 ft).
B) 5 km 16,400 ft).
C) 20 km 12.4 mi).
D) 100 km 62 mi).

Question

Quizplus · Accepted Answer

Atmospheric pressure decreases with altitude, following an exponential relationship. At around 5 km (or 16,400 ft) above sea level, atmospheric pressure is about half its sea-level value. At 1 km (or 3300 ft), atmospheric pressure is still relatively high, at around 90% of its sea-level value. At 20 km (or 12.4 mi), atmospheric pressure is less than 10% of its sea-level value, and at 100 km (or 62 mi), it is negligible. Therefore, option B is the best choice for a location where atmospheric pressure is half its sea-level value.

Atmospheric Pressure Is Half Its Sea-Level Value at an Altitude