Colt Steele
Frequent poster
Post Number: 174
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| Posted on Friday, 29
October, 2004 - 07:48 pm: |
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I do not understand what to do for this question:
Evaluate the following triple integral as a repeated integral using the
appropriate coordinate system:
where
is the unit ball
.
Any help would be great.
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Francis Woodhouse
Prolific poster
Post Number: 299
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| Posted on Friday, 29
October, 2004 - 07:56 pm: |
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Make a
change of variables to spherical coordinates. What will x
become, and what will the limits be, for the integral
over the unit ball when using spherical coordinates?
(Don't forget to multiply the integrand by the
determinant of the Jacobian of the
transformation.)
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Colt Steele
Frequent poster
Post Number: 175
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| Posted on Friday, 29
October, 2004 - 09:04 pm: |
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i do not
know how to change the variables to spherical
coordinates. I do not really know what to do with most of
the questions you have posed.
Thanx
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Francis Woodhouse
Prolific poster
Post Number: 300
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| Posted on Friday, 29
October, 2004 - 09:22 pm: |
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In a
multiple integral, if you change variables from (x,y,z)
to (u,v,w), then

where

and you multiply the integrand by the absolute value of
this determinant.
Also, remember that a change from Cartesian coordinates (x,y,z) to
spherical coordinates
is given by
.
Think about what limits you would need to cover the entire sphere of radius
after making this transformation. Be careful that each unit
volume is only covered once.
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Colt Steele
Frequent poster
Post Number: 176
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| Posted on Saturday, 30
October, 2004 - 12:04 am: |
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cheers man,
your the best.
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Colt Steele
Frequent poster
Post Number: 177
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| Posted on Saturday, 30
October, 2004 - 05:20 pm: |
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I got an
answer of 1/20*pi. Could somebody verify this.
Thanx
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Francis Woodhouse
Prolific poster
Post Number: 307
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| Posted on Saturday, 30
October, 2004 - 05:36 pm: |
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Bad news,
Colt; I got 4pi/15.
The final integral I ended up with was
.
Make sure you've got the correct limits, and that you
calculated the Jacobian correctly.
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Colt Steele
Frequent poster
Post Number: 178
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| Posted on Saturday, 30
October, 2004 - 06:02 pm: |
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I have got
a different limit for d(phi). but i do not know why it is
0-> pi and not 0-> 2*pi.
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Francis Woodhouse
Prolific poster
Post Number: 308
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| Posted on Saturday, 30
October, 2004 - 06:11 pm: |
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We only
want to traverse each unit volume of the sphere once. As
q varies from 0 to 2pi,
covering the whole radius, we only need vary phi from 0
to pi to enable all slices of the circle to be covered
(think of a circle being moved up and down the sphere,
with a line from the centre of the sphere to the
circle).
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Colt Steel
Frequent poster
Post Number: 180
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| Posted on Saturday, 30
October, 2004 - 06:52 pm: |
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thanx for
all the help
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