We can’t see air, but it is very strong. Strong enough to lift you up!
Air is all around us. This air presses in on all sides. We call this the air pressure. So the air presses on the yellow lid, as well. The air in the tank usually presses just as hard on the lid. If the air pressure in the tank is the same as that outside the tank, nothing happens.
But… the vacuum cleaner sucks out the air in the tank. So there is less air that can push back. The pressure outside the tank is far greater and it pushes the lid down. Hanging onto the lid, you move upwards.
Air pressure with suction pads
By pressing a suction cap — like the one on a plunger — against a flat surface, you push out a lot of air. Now you have a lot of air outside the suction pad that presses the suction pad against the surface. There is virtually no air left underneath that can push back. So the suction pad stays in place.
Air pressure when taking off
If the air is so strong, why don’t you constantly feel it pressing on your body?
That’s because there is a lot of air in our body, too. Just think of your lungs, your ears and your nose. The pressure from the air inside our body is more or less the same as that outside our body. So most of the time, you don’t notice anything.
But from time to time, you actually do feel the air pressure, or rather the change in air pressure. For example when taking off in an aeroplane or climbing a mountain. Because the higher you go in the air, the less air particles press on you. The result? Your ears pop! The “excess” air in your ears escapes so that the pressure difference disappears.
