Volume using double integral (polar coordiantes)

In summary, the conversation discusses using a double integral to find the volume of a solid bounded by two planes. The individual wants to use polar coordinates and confirms the setup for the integral.
  • #1
whynot314
76
0

Homework Statement


use a double integral to find the volume of the solid bounded by.

z=x^2+2y^2 and z=12-2x^2-y^2

I want to change variables using polar coordinates, I know its the top minus the bottom, and the intersection between the two is a circle radius 2.

The Attempt at a Solution



I want to make sure i have the correct set up

[itex]\int^{2\pi}_{0}[/itex] [itex]\int^{2}_{0}[/itex] (12-3r[itex]^{2}[/itex])rdrd[itex]\theta[/itex]
 
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  • #2
whynot314 said:

Homework Statement


use a double integral to find the volume of the solid bounded by.

z=x^2+2y^2 and z=12-2x^2-y^2

I want to change variables using polar coordinates, I know its the top minus the bottom, and the intersection between the two is a circle radius 2.

The Attempt at a Solution



I want to make sure i have the correct set up

[itex]\int^{2\pi}_{0}[/itex] [itex]\int^{2}_{0}[/itex] (12-3r[itex]^{2}[/itex])rdrd[itex]\theta[/itex]
That looks good !
 

Related to Volume using double integral (polar coordiantes)

1. What is the formula for calculating volume using double integrals in polar coordinates?

The formula for calculating volume using double integrals in polar coordinates is V = ∫∫f(r,θ) r dr dθ, where f(r,θ) is the function representing the shape or object and the limits of integration are based on the bounds of r and θ.

2. Can double integrals in polar coordinates be used to find the volume of any shape?

Yes, double integrals in polar coordinates can be used to find the volume of any shape as long as the shape can be represented by a function in polar coordinates.

3. How is the region of integration determined in double integrals in polar coordinates?

The region of integration is determined by the bounds of r and θ, which are determined by the shape or object being studied. The bounds must be carefully chosen to ensure that the entire region is covered and no overlap occurs.

4. What are some common mistakes to avoid when using double integrals in polar coordinates to calculate volume?

Some common mistakes to avoid when using double integrals in polar coordinates include not carefully choosing the bounds of integration, forgetting to include the r in the integrand, and not converting the function to polar coordinates if it is given in Cartesian coordinates.

5. How can double integrals in polar coordinates be applied in real-world situations?

Double integrals in polar coordinates can be applied in real-world situations such as calculating the volume of a cylindrical or spherical tank, determining the mass and center of mass of an object with varying density, and finding the volume of a rotating solid using the method of cylindrical shells.

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