Inspired by the ActionLab channel, Simon and his sister Neva have developed this interesting tool below that helps understand how human lungs and diaphragm work: the plastic bottle has a small hole in it and a balloon inside. It’s impossible to blow the balloon if the hole is closed, but once the hole is open, it’s quite easy. After Neva blows the balloon inside the bottle, she closes the hole and what happens next is like magic: the balloon is not tied, but the air inside it does not escape. Once Neva releases the hole, the air escapes. The same way, if someone’s chest is punctured, the lung can collapse. The videos below show the same experiment in slow motion using water.
The syringe (pictured below) inserted into the hole acts as the diaphragm: when you pull on the syringe to suck the air from the bottle (create vacuum inside the bottle), the balloon (the lung) blows up, filling itself with air that comes through the bottle’s opening.