- #1
Shackleford
- 1,656
- 2
I'm not understanding this integral quite fully. Of course G is the constant and rho is also a constant since the sphere is homogeneous. And pi*r'^2 dr' gives the area of circle with respect to r' with limits of a and b. However, I'm not understanding how theta comes into it and the ignoring of phi. I understand the rest of the derivation.
Of course, the integral from a to b of pi*r'^2 dr' gives an area for the annulus in the plane. I guess I'm having trouble seeing the three-dimensional derivation.
http://i111.photobucket.com/albums/n149/camarolt4z28/2010-10-03144234.jpg?t=1286135265
http://i111.photobucket.com/albums/n149/camarolt4z28/2010-10-03144253.jpg?t=1286135285
Of course, the integral from a to b of pi*r'^2 dr' gives an area for the annulus in the plane. I guess I'm having trouble seeing the three-dimensional derivation.
http://i111.photobucket.com/albums/n149/camarolt4z28/2010-10-03144234.jpg?t=1286135265
http://i111.photobucket.com/albums/n149/camarolt4z28/2010-10-03144253.jpg?t=1286135285
Last edited by a moderator: