# Homework Help: Differentiation dp/dv

1. Dec 18, 2004

### footprints

Given that pV=3600, find the value of$$\frac{dp}{dV}$$ when p= 40
I don't even know where to start?

2. Dec 18, 2004

### Nylex

Find the value of V when p = 40, then evaluate dp/dV using your value of V.

3. Dec 18, 2004

### footprints

Do you mean 40p = 3600?
Sorry I don't understand. My teacher doesn't teach very well.

4. Dec 18, 2004

### Nylex

No, set p = 40 so you get 40V = 3600 and solve for V. Then write p in terms of V, differentiate and then plug in your value of V.

5. Dec 18, 2004

### dextercioby

$$Vp(V)=3600;p(V)=\frac{3600}{V}$$.

Question:what is $$\frac{dp(V)}{dV}$$ ??

Daniel.

6. Dec 18, 2004

### footprints

Got it. Thanks. Last question. Why do I have to find V? Or how do I know I have to find V?

7. Dec 18, 2004

### Nylex

Well because you're asked to find a value for dp/dV and your expression for dp/dV will be in terms of V and not p.

8. Dec 18, 2004

### footprints

Oh right. Thanks a lot. Really appreciate it.