# Relative rates of change

1. Dec 14, 2006

### flash9286

if you have a*v=s*w how do you get:

delta a/a+delta v/v=delta s/s+delta w/w

can anybody explain why this is true.

2. Dec 14, 2006

### arildno

Well, fiddle about with the expression:
$$(a+\delta{a})(v+\delta{v})=(s+\delta{s})(w+\delta{w})$$

3. Dec 14, 2006

### flash9286

I'm sorry I don't follow

4. Dec 14, 2006

### arildno

What do you not follow?
Do you not understand that the equation av=sw holds for different choices of "a", "s", "v" and "w", including the choices $(a+\delta{a}),(s+\delta{s}),(v+\delta{v}),(w+\delta{w})$?

5. Dec 14, 2006

### flash9286

Nevermind I got it. Thanks for your help