1. The problem statement, all variables and given/known data Calculate the frequency of: (a) the fundamental, (b) the first overtone, produced by a pipe of length 40 cm which is closed at each end. (Velocity of sound in air = 340 m s-1.) Answers: (a) 425 Hz, (b) 850 Hz 2. The attempt at a solution L = 0.4 m, v = 340 m s-1 (a) f1 = ? fn = nv / 2L f1 = 1 * 340 / 2 * 0.4 = 425 Hz (b) f2 = ? f2 = 2f1 f2 = 2 * 425 = 850 Hz The answer fits but I used the formulas which are for open pipes. When I used the formulas for the closed pipes I got wrong answers (212.5 Hz and 637.5 Hz). Why "closed pipe at each end" is considered an open pipe? Or maybe I used the formulas wrong and the solition is different?