eli5 why does it make a loud bang when you pop a plastic bag or bubble wrap?
Fun fact. Sudden change in pressure can go both ways to create a sound wave. Release of sudden high pressure (popping a bag) And sudden decrease of pressure. The fun thing about this to me, is the strange accuracy of teleportation in Harry Potter. Removing a person sized volume instantly from space, would create a pretty good sized vacuum of space that would collapse, and make a loud bang, just like in the story.
sound is just air moving back and forth rapidly. When you move air enough it creates sound create sound. Imagine wind blowing lightly into your ear. Even though its moving in one direction it causes the air molecules to vibrate also.
So when you pop a plastic bag, it causes the air to be compressed. When it suddenly decompresses, it causes the air to move back and forth rapidly. Which creates the sound.
not a physicist but it’s probably as simple as you’d think it is. lots of pressure built up to the point where it simultaneously ruptures the material and releases all that pressure. not sure if that’d make it fall under the technical category of an explosion per se, since theres no real chemical reactions happening here, but it’s similar to why a gunshot is so loud. lots of pressure being released at once.