Length of a closed pipe is 75 cm. First overtone of this closed pipe beats with the first over tone of an open pipe with a beat frequency of 5 Hz. If velocity of sound in air is 330 Hz, what is the length of the open pipe ?

First overtone of closed pipe = (f1)CFirst overtone of open pipe = (f1)0f1C =  3  .  V4lC =  3 × 3304  ×  0.75  Hz  =  330  Hzf10 =  4  .  V4l0 =   330l0 . HzNow   330l0 − 330 =5  ⇒  l0 = 0.985  m=98.5  cm.Again,  330 −  330l0  =5  ⇒  l0 = 1.015  m=101.5  cm.