Air is heavy enough to crush us, but why doesn’t it? Why do we often make the mistake of thinking air weighs nothing?
Air is very heavy. Your room probably contains more than 100 kilogram of air.(depends on how big your room is) On every square centimetre of Earth, air presses with a force of about 10 newtons. That means there is a force of about 10 newtons (1 kg) on your fingernail.
Why are we not crushed? Air presses in all directions. Not just downwards, but sideways and upwards as well. That is why we are not pushed down flat.
All that weight of air pushes down from above, but we can still walk about because the air pushes up from below as well. And there’s air inside us too to withstand outside pressure. So we don’t feel the pressure of air and think air weighs nothing.