https://en.wikipedia.org/wiki/Whipcracking https://en.wikipedia.org/wiki/Whipcracking "The crack a whip makes is produced when a section of the whip moves fast

https://en.wikipedia.org/wiki/Whipcracking https://en.wikipedia.org/wiki/Whipcracking "The crack a whip makes is produced when a section of the whip moves faster than the speed of sound creating a small sonic boom." (I agree that is a strangely satisfying thing. It does make hanging the wash up for drying slightly less tedious...)