Triple integral in polar coordinate

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SUMMARY

The discussion centers on the representation of coordinates in polar and spherical systems, specifically the equations x = ρ cos(θ) sin(φ), y = ρ sin(θ) cos(φ), and z = ρ cos(φ). Participants clarify that φ is the angle between the z-axis and the line from the origin to the point in space, not between p and z. The conversation emphasizes the importance of understanding the distinction between the Greek letters ρ (rho) and φ (phi) in these contexts, as well as the proper interpretation of diagrams related to these coordinate systems.

PREREQUISITES
  • Understanding of polar and spherical coordinate systems
  • Familiarity with trigonometric functions and their applications
  • Knowledge of Greek letters used in mathematics, specifically ρ (rho) and φ (phi)
  • Ability to interpret mathematical diagrams accurately
NEXT STEPS
  • Study the derivation of spherical coordinates from polar coordinates
  • Learn about the applications of spherical coordinates in physics and engineering
  • Explore the differences between polar and cylindrical coordinate systems
  • Review common mistakes in interpreting coordinate diagrams and how to avoid them
USEFUL FOR

Students studying calculus, physics enthusiasts, and anyone seeking to deepen their understanding of coordinate transformations in three-dimensional space.

chetzread
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Homework Statement


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


Homework Equations

The Attempt at a Solution

 
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Why would you think that?
Well, as I see it, ##\phi## is the angle between ##z## and ##\rho##.
 
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Mr-R said:
Why would you think that?
Well, as I see it, ##\phi## is the angle between ##z## and ##\rho##.
really? then where is p?
P is on the same line as x-axis, am i right?
 
chetzread said:
really? then where is p?
P is on the same line as x-axis, am i right?

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:
 
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https://www.physicsforums.com/members/chetzread.597855/
You had better start from 2D - the polar coordinates, trying to understand, why x = ρ cos Θ and y = ρ sin Θ.
 
chetzread said:
why x is p(cosθ)(sinφ) ? and y=p(sinθ)(cosφ)?
z=p(cosφ)
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.
 
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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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