# An organ pipe is 84 cm long and at a temperature of 20 degrees C.

1. Dec 14, 2008

### JohnnyB212

1. The problem statement, all variables and given/known data

An organ pipe is 84 cm long and at a temperature of 20 degrees C. What is the fundamental (in Hertz) if the pipe is closed at one end?

2. Relevant equations

To best honest, I'm not really to sure where to start. Can anyone please help? Start me off?

2. Dec 14, 2008

### Mthees08

Start off drawing a picture! nodes and anti-nodes this will show you the ratio of length of the pipe to the wave length! If you need more help just say so I am going to use this as an exercise to review harmonics so i will find the answer.

3. Dec 14, 2008

### JohnnyB212

The picture alone doesn't really help me much though.

4. Dec 14, 2008

### Mthees08

well if you draw it you see you have 1 node 1 antinode which means the length of the pipe is 1/4 the wavelength the speed of sound at 20C is 344 m/s freq=v/wavelength. Thats really all I can say without telling you the answer lol

5. Dec 14, 2008

### JohnnyB212

lol Gosh i'm sorry, i'm still confused, Iv'e been working on this stuff all day preparing for my physics final tomorrow, and i'm extremely confused.

does the equation Fn = n * (v / 4L) have anything to do with it?

6. Dec 14, 2008

### Mthees08

Don't worry about being confused, it can get that way especially when you start adding ns and random variables in. If you look that is the equation I gave you, with 2 ns in it, which if I remember correctly correspond to the number of nodes maybe? I am not sure, however I believe they are there simply to confuse you. They might be the harmonics of a pipe,

Fn = (n+1)*(V/4L) is the relation that I would use to describe number of nodes to the frequency of a pipe with 1 end open So if you explain n I might be able to help explain that equation but it is not one I am familiar with.

Hint: Closed ends have nodes, open ends have anti-nodes

7. Dec 14, 2008

### JohnnyB212

OH! I got it!

Since there was 1 node and 1 antinode, I assumed it canceled out, I simply put in

344 / (4 * .84)

And it was correct lol, Thanks for your help! I appreciate this!