A thin nylon cord weighs 8.50 g and is held taught by a force of 425 N. It is 40.0 cm in length. When this cord is vibrating in its fourth harmonic, you observe that it causes a tube, open at both ends, to resonate in its third harmonic frequency. Suppose that the speed of sound is 344 m/s.
a) How long is the tube?
b) What is the fundamental frequency of the tube?