Chapter 14, Problem 88GP

Playing Harmonics When a 63-cm-long guitar string is plucked, all possible standing waves simultaneously exist on the string. When you place your finger on the string, any standing waves with nonzero amplitude at that location are stopped, but any standing waves with a node at that location continue vibrating. If you wish to stop all standing waves with frequencies lower than the third harmonic on this string, how far from the end of the string should you place your finger?