
Calculus Calculus Math Forum 
 LinkBack  Thread Tools  Display Modes 
January 3rd, 2017, 06:24 AM  #1 
Member Joined: Oct 2016 From: Sverige Posts: 30 Thanks: 2  Integrate over sphere issue (URGENT)
So I'm suppose to integrate over a sphere w. radius 3. It has the surface charge $\displaystyle w = e^r * sinu * sin^2v$ To integrate I want to find: n dS, n being normal vector, dS delta surface aka. du dv. Normal vector = sphere coordinate normalized = $\displaystyle n = (sinu * cosv, sinu*sinv, cosu)$ $\displaystyle n dS = n dudv$ ?? But in my book they get: $\displaystyle ndS = (+ r^2sinu, 0, 0)$ I have no idea how they just deleted 2 out of 3 axis when integrating over a sphere. All help is appreciated, got final exam in less than a week. 
January 3rd, 2017, 07:45 AM  #2 
Math Team Joined: Jan 2015 From: Alabama Posts: 2,570 Thanks: 667 
In spherical coordinates, the radial axis is perpendicular to the sphere so the $\displaystyle \theta$ and $\displaystyle \phi$ components (called "u" and "v" here) are 0.


Tags 
integrate, issue, sphere, urgent 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Need help on this issue  Frontier111  Physics  9  May 13th, 2016 03:18 AM 
Tax issue  bigcity  Algebra  3  January 2nd, 2012 11:09 AM 
Time issue  daemonlies  Elementary Math  1  August 21st, 2011 04:08 PM 
Sphere and integral..need urgent help  tinyone  Calculus  0  November 18th, 2010 01:38 PM 
Time issue  daemonlies  Applied Math  1  December 31st, 1969 04:00 PM 