a church pipe organ consists of several pipes that generate sound waves. pipe a of the organ is open at both ends and has a length l. pipe b of the organ is identical to a, except that it has one open end and one closed end. when a is played in its third harmonic and b is played in its fundamental mode, beats having a frequency fb = 86 Hz are generated. Given that the speed of sound when the beats are created is v = 344 m/s, the length of pipes A and B is
A. 10 M
B. 5.0 M
C. 3.5 M D. 2.0 M
E. 7.0 M