About GitHub Coach Log in Start reading

Physics · Glossary

What is Atmospheric pressure?

Definition 7.7 High School Physics · Chapter 7 — Pressure: From Sport to Diving

We live at the bottom of an ocean of air, whose weight creates the atmospheric pressure, at sea level

P0≈101 kPa=1.01×105 Pa.P_0 \approx 101\,\mathrm{kPa} = 1.01 \times 10^{5}\,\mathrm{Pa}.

On each square centimetre this is F=1.01×105×1×10−4≈10 NF = 1.01 \times 10^{5} \times 1 \times 10^{-4} \approx 10\,\mathrm{N}: the weight of a one-kilogram mass on every cm2\mathrm{cm}^{2} of your skin, your desk, everything.

Examples

Example 7.8 (The invisible load)

An A4 sheet of paper (21.0 cm21.0\,\mathrm{cm} ×\times 29.7 cm29.7\,\mathrm{cm}, so S≈0.0624 m2S \approx 0.0624\,\mathrm{m}^{2}) receives from the air above it F=1.01×105×0.0624≈6.3×103 NF = 1.01 \times 10^{5} \times 0.0624 \approx 6.3 \times 10^{3}\,\mathrm{N} — the weight of a small car. Nothing tears: the air below pushes up just as hard. We notice the atmosphere only when one side loses it — a suction cup, a straw, an aircraft cabin.

Read in context →

Related terms