sound waves?

Question

A variabled length of open pipe...(a smaller pipe inside a larger pipe)...when the pipe is fully retracted it produces a fundimental note of 256Hz when blown in an end. What is the effective length of the inner pipe if it is considered to be an open pipe?

Answer 1

Ok, well, what I remember about sound waves is that in an inner pipe or tube you have a fundamental note or frequency :

F1 = v / 2L

where v is the velocity of the wave

So if we consider V = velocity of the sound = 340 m/s

256 = 340 / 2l

2L = 340 / 256

L = 1.33 (meters)

You just need to remember waves in inner tubes like organs for example.