Volume in cylindrical coordinates

Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
1 reply · 2K views
physics&math
Messages
14
Reaction score
0

Homework Statement



Find the volume using cylindrical coordinates bounded by:

x2+y2+z2=2 and

z = x2+y2

Homework Equations



Converting to cylindrical coordinates:
z = √2-r2 and

z = r2

The Attempt at a Solution



I figured z would go from r2 to √2-r2
r from 0 to √2
and θ from 0 to 2∏.
However, when I evaluate the integral I get a negative volume. (And no, I did not forget to multiply by an extra r)

I have no idea where I've gone wrong.
 
Physics news on Phys.org
physics&math said:

Homework Statement



Find the volume using cylindrical coordinates bounded by:

x2+y2+z2=2 and

z = x2+y2

Homework Equations



Converting to cylindrical coordinates:
z = √2-r2 and

z = r2

The Attempt at a Solution



I figured z would go from r2 to √2-r2
r from 0 to √2
and θ from 0 to 2∏.
However, when I evaluate the integral I get a negative volume. (And no, I did not forget to multiply by an extra r)

I have no idea where I've gone wrong.

What is the x,y equation of the intersection of your two surfaces? Are you sure you copied the problem correctly?