# Homework Help: Volume in spherical coordinates

1. May 2, 2012

### rc3232

1. The problem statement, all variables and given/known data
Calculate volume of the solid region bounded by z = √(x^2 + Y^2) and the planes z = 1 and z =2

2. Relevant equations

3. The attempt at a solution

2. May 2, 2012

### dikmikkel

Edit: You could visualize it and integrate over 1 and add these volumes.

Last edited: May 2, 2012
3. May 2, 2012

### RC32

it's a cone, but how do you set the limits for the different integrals in spherical coordinates?

4. May 2, 2012

### The Gringo

In sphereical coordinates you know that $x=\rho\cos\theta\sin\phi$, $y=\rho\sin\theta\sin\phi$ and $z=\rho\cos\phi$
You can use this to find limits for $\rho$.
If you draw the x-z or y-z plane intercept this can help you find $\phi$

5. May 2, 2012

### sharks

You should first plot it to know what the volume looks like.

The volume between z=1 and z=2 is that of a circular disk. You need to use cylindrical coordinates.

Description of the region:
For r and θ fixed, z varies from z=1 to z=2
For θ fixed, r varies from r=1 to r=√2
θ varies from θ=0 to θ=2∏

Plug the limits into the triple integral and evaluate to find the required volume:
$$\int \int \int dr d\theta dz$$

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