Question

The average circumference of the human chest is 97cm to 114cm. Let us, for the sake of simplicity, assume that this is a circle. The cross-sectional area of the human body then is ≈3×(0.97/6)²=0.08 m² (taking the lower limit 97 cm). The atmosphere extends roughly 12 km vertically = 12000 m. The volume of air then, pressing on top of our bodies, is = 0.08×12000=960 m³. The density of air is roughly 1 kg/m³. So the weight of the air an average person has to bear = 1×960=960 kg. How come we don't feel this 960 kg weight (9408 Newtons) of air?

Answer 1

We don't feel the weight of air due to atmospheric pressure being evenly spread across our bodies, and because our bodies are internally pressurized. The density of air also decreases with altitude, affecting atmospheric pressure.

Step-by-step explanation:

The reason we do not feel the weight of air is due to atmospheric pressure, which is exerted evenly across our bodies. Although the weight of the air above us is significant—about 960 kg—the pressure is distributed equally over our entire body surface. This uniform distribution of pressure means that it doesn't press down on us with a force we can feel as a singular weight. Additionally, our bodies are internally pressurized to counteract the external atmospheric pressure, preventing us from being crushed by it. The average density of air at sea level is approximately 1.29 kg/m³ and decreases with altitude because air is compressible. This explains why high-altitude environments have lower atmospheric pressure, leading to scenarios where mountain climbers need supplemental oxygen due to the thin air.