Bennett Mechanical Comprehension Practice Test 2025 - Free Practice Questions and Review Guide

At an altitude of 100 km above the Earth's surface, air pressure significantly decreases compared to sea level. At sea level, air pressure is defined as 1 atmosphere (atm). However, as altitude increases, the density of air decreases due to the gravitational pull on air molecules being weaker at higher elevations. Consequently, the number of air molecules available in a given volume diminishes, leading to a drop in air pressure.

Thus, at 100 km, which reaches into the lower thermosphere, the air pressure is indeed less than 1 atm, typically in the range of 0.001 atm, indicating an extremely thin atmosphere. This decrease in air pressure with altitude is a fundamental principle of atmospheric science and is well-established in meteorological studies.

Understanding how air pressure varies with altitude can be crucial for applications ranging from aviation to weather prediction and even in the design of various mechanical systems that operate under different pressure conditions.