# Thread: Wave Motion/Musical Note Frequencies

1. You invent a new musical instrsument, the phonitar, which combines strings and pipes. You design it such that the fundamental frequencies of the two strings and one closed pipe form a G major chord (G-B-D) on a normal day (20 degrees C). The two strings both have a mass/length density of 0.0082 kg/m and are palced under equal tension of 600 N.

a. How long must the bass string be in order to produce the note that is one obctave lower than the G above middle C as its fundamental frequency?

b. How long must the other string be to produce the D above midddle C note as its fundamental frequency?

c. How long must the closed pipe be to produce a B note as its fundamental frequency (B below middle C)?

You are invited to perform a phonitar concerto at the Siberian Symphony located in Yakutsk. The temperature for today's outdoor performance is a balmy -12.7 degrees Celsius.

d. What fundamental notes do the two strings on your instrument produce on this cold day?

e. What fundamental note does the closed pipe play?

And here is the table with the frequencies:

Note Hz

A# or Bb 233

B 247

Middle C 262

C# or Db 277

D 294

D# or Eb 311

E 330

F 349

F# or Gb 370

G 392

G# or Ab 415

A 440

A# or Bb 466

B 494

2. Dear Pietro,

Welcome to the forum. This sounds like a homework problem and as such it belongs in the homework forum which is at
Homework Help

The rules of that forum are at
READ FIRST BEFORE POSTING - Homework Help Guidelines

If it's not a homework problem then you should at least explain what's going on here. It sounds like work or an invention and we don't do someone else's work for them or create things for other people.

3. Originally Posted by Pietro
You invent a new musical instrsument, the phonitar, which combines strings and pipes...
Welcome to the Forum. It appears that you have posted a homework problem. Forum policy is not to do homework, but if you describe what you have tried and where you've gotten stuck, someone here may be able to help you get unstuck.

4. Originally Posted by Physicist
Dear Pietro,

Welcome to the forum. This sounds like a homework problem and as such it belongs in the homework forum which is at
Homework Help

The rules of that forum are at
READ FIRST BEFORE POSTING - Homework Help Guidelines

If it's not a homework problem then you should at least explain what's going on here. It sounds like work or an invention and we don't do someone else's work for them or create things for other people.
Hi, this question is not really a homework problem as I am not taking a course currently. It is basically an implementation of the frequencies of the musical notes and questions pertaining to that. If you do believe that it is a homework problem, then I shall post it there also. I just want to find out how to solve this type of problem.

5. Great vibrations and waves quiz, especially its music flavor. I'd really need to get back to my SHM physics and maths. A handful of guys can do this here.

6. Originally Posted by Pietro
Hi, this question is not really a homework problem as I am not taking a course currently. It is basically an implementation of the frequencies of the musical notes and questions pertaining to that. If you do believe that it is a homework problem, then I shall post it there also. I just want to find out how to solve this type of problem.
A quick google search for "phonitar" turns up a few links that suggest that this very question -- in precisely this form -- has been used as a homework problem in the past.

That said, it is still helpful to us to know how you have tried to solve the problem. Where have you gotten stuck?

And if this is just for self-study, why this particular problem, instead of a simpler problem involving, say, a single string to start?

7. Originally Posted by Pietro
Hi, this question is not really a homework problem as I am not taking a course currently.
Dear Pietro,

First off please allow me to welcome you to the forum!

On with your question; The requirements for discussing problems such as this in this forum are posted at - Model procedure for solving physics problems

Ideally the rules were designed so that students who come here will
(1) Be able to find the solution to the problem they're asking for help with and to do it themselves instead of getting someone to do it for them
(2) Make sure that the forum members aren't doing homework for students who come here
(3) Weed out cheaters, i.e. students people who are lying, i.e. claiming that the problem that they're asking for help with is not homework.

You must surely be able to see our concern for #2 and #3. If a cheater wants to get someone to go their homework for them then when asked if it's homework then it's nearly certain that they're lying.

For learning purposes it's not helpful to the student to have someone to do their work for them since you don't learn that way. If you know how to demonstrate that this is not homework then that's an entirely different story. In that case a person might just need an expert to have them answer a question for them. They might not be interested in the subject matter themselves.

You're fortunate in this case because it doesn't appear to be a physics problem since physics problems don't phrase questions using terms such as
G major chord

obctave

D above midddle C note

c. How long must the closed pipe be to produce a B note as its fundamental frequency (B below middle C)?
etc. So it I had time I'd probably help you. However in cases such as this I spend my time helping people who ask questions which I can more easily answer rather than instead of going into my bookcase and learning about the physics and terminology of music. Hard for me? No. I'm just not interested. Sorry.

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