# Homework Help: Charged Shape Described by a Function - Urgent

1. Oct 13, 2011

### acedeno

Last edited by a moderator: May 5, 2017
2. Oct 14, 2011

### SteamKing

Staff Emeritus
For part b) if p(x,y,z) were the material density in grams / cc and the surface of the object made out of this material had the equation x^2+y^z = a*z, how would you calculate the total mass of the object? For part b), instead of density, assume p(x,y,z) is the amount of charge over a unit portion of the volume of the object.

3. Oct 14, 2011

### acedeno

I'm sorry but I'm really not following. I guess I could find mass by using m=(density)(volume) but I'm still uncertain on how to express the volume of this object.

4. Oct 14, 2011

### Clever-Name

Do you recognize:

$$Q = \int_{\mathcal{V}} \rho d\tau^{'}$$

This is the general equation for total charge over a volume with a given charge density

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