1. The problem statement, all variables and given/known data An instrument is producing a tone, such as a D4. If I know the frequency of the tone, the length of the instrument but nothing else, how can I find the harmonic at which the tone is produced? The instrument is an open tube. 2. Relevant equations v=wavelength*frequency L=n*wavelength/2 3. The attempt at a solution The point of the overall problem is to calculate the speed of sound using the length and frequency, but I don't know what equation to use to find the velocity since the harmonic number is not given.