# Fundamental Frequency

1. Jan 6, 2005

### Soaring Crane

Which of the following could be the fundamental freq. for a vibration that has an overtone freq. of 990 Hz?

a. 330
b. 660
c. 148
d. 1980
e. 1990
(All in Hz.)

The formula that I think you have to use is f_n = n*f_1, where f_1 is fud. freq.

Then, I thought

f_2 = 2*f_1, where f_2 is the overtone freq. (is these a correct assumption?)

but 990/2 is 495.

Could someone direct me to the correct path of getting the solution?

I'm confused over the definitions of overtone and fund. freq.

Thanks.

Last edited: Jan 6, 2005
2. Jan 6, 2005

### Gokul43201

Staff Emeritus
There's no reason to assume than n=2, so you just leave it as n.

So you have $f_n = nf_1$
Or $f_1 = \frac {990}{n}$

Which of the choices satisfies this condition for some integer n ?

Can you say if $f_1$ will be greater than or less than 990 Hz, from this ? Does this rule out any choices ?

The alternative is simply to notice that $f_n/f_1 = n$, so try the remaining choices of $f_1$ to see which one gives you an integer ratio.

Last edited: Jan 6, 2005
3. Jan 6, 2005