Cone with spherical top triple integration

Click For Summary
The discussion focuses on solving a triple integral for a cone with a spherical top, where the user initially sets bounds for the integral in rectangular coordinates. They express concern about the complexity of the integral and inquire about the possibility of using polar coordinates for simplification. Another participant suggests setting up the problem in spherical coordinates but acknowledges the user's preference for rectangular coordinates for practice. They recommend integrating the dz integral first, which would simplify the problem to a double integral over a circle in the xy-plane. The conversation emphasizes the transition from rectangular to polar coordinates to facilitate the integration process.
Digitalism
Messages
40
Reaction score
7

Homework Statement



QRWR5E8.png



Homework Equations



∫∫∫dV

The Attempt at a Solution



Ok so I started by setting my bounds equal to √(200-x^2-y^2) ≥ z ≥ √(x^2+y^2), √(100-x^2) ≥ y ≥ -√(100-x^2), 10 ≥ x ≥ -10

which I got from solving z^2 = (200-x^2-y^2) = x^2+y^2 => x^2+y^2 = 100 but it seems to be a very messy integral. Should I try integrating differently? Is there a way to do this using polar coordinates?
 
Physics news on Phys.org
Digitalism said:

Homework Statement



QRWR5E8.png



Homework Equations



∫∫∫dV

The Attempt at a Solution



Ok so I started by setting my bounds equal to √(200-x^2-y^2) ≥ z ≥ √(x^2+y^2), √(100-x^2) ≥ y ≥ -√(100-x^2), 10 ≥ x ≥ -10

which I got from solving z^2 = (200-x^2-y^2) = x^2+y^2 => x^2+y^2 = 100 but it seems to be a very messy integral. Should I try integrating differently? Is there a way to do this using polar coordinates?

Set it up in spherical coordinates.
 
sorry, I haven't learned that yet and I think this problem was explicity set up in rectangular so I could practice learning these in rectangular I am simply unsure how to place pi in there also :/
 
If you have had polar coordinates but not spherical coordinates, take your xyz integral (which is set up correctly) and integrate the dz integral. That will leave you a double integral over the circle ##x^2+y^2 = 100## in the xy plane. Change that integral to polar coordinates using ##r^2=x^2+y^2,~dydx=rdrd\theta## and put ##r,\theta## limits for the circle on the integrals.
 
  • Like
Likes 1 person
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

Similar threads

  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 9 ·
Replies
9
Views
2K
Replies
3
Views
2K
  • · Replies 19 ·
Replies
19
Views
2K
  • · Replies 12 ·
Replies
12
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
Replies
2
Views
1K
  • · Replies 3 ·
Replies
3
Views
1K
Replies
6
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K