Triple Integrals: Finding Mass of a Bounded Solid

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SUMMARY

The discussion focuses on calculating the mass of a solid with constant density, bounded by the parabolic cylinder defined by x=y² and the planes x=z, z=0, and x=1. Participants emphasize the importance of correctly setting the limits of integration when using triple integrals. Specifically, the correct order of integration should be x, y, then z, with limits for x ranging from z to 1, and y from -√x to √x. Visualizing the problem with 3D diagrams is recommended to avoid confusion in determining the limits.

PREREQUISITES
  • Understanding of triple integrals in calculus
  • Familiarity with parabolic cylinders and their equations
  • Knowledge of integration limits and their implications
  • Ability to visualize three-dimensional solids
NEXT STEPS
  • Study the application of triple integrals in finding volumes and masses
  • Learn about changing the order of integration in multiple integrals
  • Explore the use of 3D graphing tools to visualize complex solids
  • Review the properties of parabolic cylinders and their geometric implications
USEFUL FOR

Students studying calculus, particularly those focusing on multivariable integration, as well as educators looking for examples of applying triple integrals to real-world problems.

theBEAST
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Homework Statement


Find the mass of a solid of constant density that is bounded by the parabolic cylinder x=y2 and the planes x=z, z=0, and x=1.

The Attempt at a Solution


https://dl.dropbox.com/u/64325990/Photobook/Photo%202012-06-07%202%2033%2024%20PM.jpg

I first drew some diagrams to help me visualize the problem and then I tried to solve this integral but it ended up to be in terms of x. What am I doing wrong?
 
Last edited by a moderator:
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If you want to integrate in the order x, then y then z, then...

For an arbitrary (y,z), x should go from the z=x plane to the x=1 plane,
that is, x=z..1.

For an arbitrary z, y should go from -√x to √x.

Then z should go from 0 to 1.

So your last limit should not be a function of x, nor y.You may want to draw all surfaces in one 3d pic. so you can see that the lower limit in x should have been x=z, not x=y^2.
You may want to consider othe orders of integration, so that you avoid the square roots.
 
theBEAST said:

Homework Statement


Find the mass of a solid of constant density that is bounded by the parabolic cylinder x=y2 and the planes x=z, z=0, and x=1.

The Attempt at a Solution


https://dl.dropbox.com/u/64325990/Photobook/Photo%202012-06-07%202%2033%2024%20PM.jpg

I first drew some diagrams to help me visualize the problem and then I tried to solve this integral but it ended up to be in terms of x. What am I doing wrong?
If you integrate w.r.t. x first (inner integral)n then there shouldn't any x in the limits of the outer two integrals.
 
Last edited by a moderator:

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