My Math Forum  

Go Back   My Math Forum > College Math Forum > Calculus

Calculus Calculus Math Forum

LinkBack Thread Tools Display Modes
January 3rd, 2017, 06:24 AM   #1
Joined: Oct 2016
From: Sverige

Posts: 32
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.
Addez123 is offline  
January 3rd, 2017, 07:45 AM   #2
Math Team
Joined: Jan 2015
From: Alabama

Posts: 3,264
Thanks: 902

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.
Country Boy is offline  

  My Math Forum > College Math Forum > Calculus

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

Copyright © 2019 My Math Forum. All rights reserved.