1. The problem statement, all variables and given/known data Open and closed pipe, give 5 beats per second. Open pipe is 30 cm long and gives a tone of frequency f0. Speed of sound is 330 m/s. How long do we need to extend closed pipe so both pipes give equal frequencies? 2. Relevant equations Open pipe, fn=n*f1, f1=v/(2L) Closed pipe; fn= f*f1, f1 = v/(4L) fbeat = f2 - f1 3. The attempt at a solution For open pipe, I assume that f0 is f1, or basic frequency. f=v/2L=330 ms-1 / 0,6 m = 550 Hz fbeat = f2 - f1 5 = f2 - 550 Hz f2 = 555 Hz. Now we need to find the lenght of open pipe. 4L = v/f2 l= v/4f2= 0,15 m Since i have the lenght of closed pipe, motive is to adjust it so we have frequency of 550 Hz. 4L = v/f2, 4*L = 330 ms-1/ 550 Hz 4*L = 0,6 m L = 0,15 What did I do wrong?