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Triple integral in polar coordinate

  1. Jul 9, 2016 #1
    1. The problem statement, all variables and given/known data
    why x is p(cosθ)(sinφ) ? and y=p(sinθ)(cosφ)?
    z=p(cosφ)

    As we can see, φ is not the angle between p and z .......
    QFLKD8u.jpg

    2. Relevant equations


    3. The attempt at a solution
     
  2. jcsd
  3. Jul 9, 2016 #2
    Why would you think that?
    Well, as I see it, ##\phi## is the angle between ##z## and ##\rho##.
     
  4. Jul 9, 2016 #3
    really? then where is p?
    P is on the same line as x-axis, am i right?
     
  5. Jul 9, 2016 #4
    Nope it is not on the same axis as x. If that was the case then the equation ##x^2+y^2+z^2=\rho^2## wouldn't make sense.
    If you are bothered by the provided diagram then just look up another one from another source :wink:
     
  6. Jul 9, 2016 #5

    ehild

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  7. Jul 10, 2016 #6
    chetzread
    You had better start from 2D - the polar coordinates, trying to understand, why x = ρ cos Θ and y = ρ sin Θ.
     
  8. Jul 10, 2016 #7

    vela

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    That's a really bad figure. No wonder you're confused. Check out the page ehild linked to.

    By the way, ##\rho## is the Greek letter rho. It's not P nor p.
     
  9. Jul 26, 2016 #8

    BvU

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    Can I also point out that physicists use ##\theta## for the polar angle and ##\phi## for the azimuthal angle ?
    Much more consistent with the cylindrical ##(\rho,\phi,z)## coordinate system :smile:

    So: stay alert to avoid miscommunication !
     
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