And why are Grand Pianos Shaped That Way?

From Fermat's Library's Twitter feed:

The reason why the shape of a lot of pianos looks like an exponential is because for waves on a string, doubling length means reducing a music pitch by an octave (2x the frequency). pic.twitter.com/x75mIzl2K7

— Fermat's Library (@fermatslibrary) October 17, 2019