# Rearranging the doppler effect formula to solve for Vs

1. Jan 18, 2009

### hellokitty

I know which equations to use for solving Doppler Effect problems, so figuring out which is the observer and which is the source and which is moving or stationary is not the problem, the problem I am having is in solving the actual formulas...... This question might belong in the math help section but I thought it was best to post this in the physics area because it does deal with a physics topic.

Anyway, I attached the equations as graphics (maybe somebody knows how to LATEX these?). I am looking for some help in rearranging these equations to solve for each of the variables, V,Vs,Vo,Fo,Fs.

#### Attached Files:

• ###### untitled.bmp
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2. Jan 18, 2009

### Staff: Mentor

Here's a latex version of that formula (which applies when the observer is stationary but the source moves):

$$f_o = f_s \frac{v}{v \pm v_s} = f_s \frac{1}{1 \pm v_s/v}$$

Do you have an example of the kind of problem that is giving you trouble?

3. Jan 18, 2009

### hellokitty

the problem is asking to solve for Vs from the formula that I have attached. But I do not know how to rearrange it to where I can solve for Vs. I have everything else in the formula but I do not know how to rearrange it...

4. Jan 18, 2009

### Staff: Mentor

Do it step by step:

$$f_o = f_s \frac{1}{1 \pm v_s/v}$$

$$\frac{f_o}{f_s} = \frac{1}{1 \pm v_s/v}$$

$$\frac{f_s}{f_o} = 1 \pm v_s/v$$

You take it from here.