Question

The unsupported flagpole built for Canada’s Expo 86 has a height of 86 m. If a standing wave with a 19th harmonic is produced in an 86 m open pipe, what is its frequency? The speed of sound in air is 334 m/s

Answer 1

The frequency of the 19th harmonic:

$$f_{19}=n\frac{c}{2L}=19\frac{334}{2·86}=37\text{ Hz}.$$