Math Problem Statement

Convert the integral
∫ 7 − 7 ∫ √ 49 − y 2 0 ∫ √ 49 − x 2 − y 2 − √ 49 − x 2 − y 2 − 4 ( x 2 + y 2 + z 2 ) 2 d z d x d y from rectangular to spherical coordinates. Do not evaluate the integral.

Solution

To convert the given triple integral from rectangular coordinates to spherical coordinates, let's break the process into steps.

Original Integral:

77049y249x2y249x2y24(x2+y2+z2)2dzdxdy\int_{-7}^{7} \int_{0}^{\sqrt{49 - y^2}} \int_{-\sqrt{49 - x^2 - y^2}}^{\sqrt{49 - x^2 - y^2}} -4(x^2 + y^2 + z^2)^2 \, dz \, dx \, dy

1. Recognize the bounds in rectangular coordinates:

  • x2+y2+z2=49x^2 + y^2 + z^2 = 49: This represents a sphere with radius 77.
  • The limits on x,y,zx, y, z describe a solid sphere centered at the origin with radius 77.

2. Express the integrand in spherical coordinates:

In spherical coordinates:

  • x=ρsinϕcosθx = \rho \sin\phi \cos\theta,
  • y=ρsinϕsinθy = \rho \sin\phi \sin\theta,
  • z=ρcosϕz = \rho \cos\phi,
  • x2+y2+z2=ρ2x^2 + y^2 + z^2 = \rho^2,
  • The volume element is dV=ρ2sinϕdρdϕdθdV = \rho^2 \sin\phi \, d\rho \, d\phi \, d\theta.

The integrand 4(x2+y2+z2)2-4(x^2 + y^2 + z^2)^2 becomes: 4(x2+y2+z2)2=4ρ4-4(x^2 + y^2 + z^2)^2 = -4\rho^4

3. Determine the bounds in spherical coordinates:

  • ρ\rho: Radius ranges from 00 to 77 (since the sphere's radius is 7).
  • ϕ\phi: Polar angle ranges from 00 to π\pi (full vertical sweep).
  • θ\theta: Azimuthal angle ranges from 00 to 2π2\pi (full horizontal sweep).

4. Write the integral in spherical coordinates:

Substitute the integrand and bounds into the spherical coordinate integral:

02π0π074ρ4ρ2sinϕdρdϕdθ\int_{0}^{2\pi} \int_{0}^{\pi} \int_{0}^{7} -4\rho^4 \cdot \rho^2 \sin\phi \, d\rho \, d\phi \, d\theta

Simplify the volume element ρ4ρ2\rho^4 \cdot \rho^2: 02π0π074ρ6sinϕdρdϕdθ\int_{0}^{2\pi} \int_{0}^{\pi} \int_{0}^{7} -4\rho^6 \sin\phi \, d\rho \, d\phi \, d\theta

Final Expression:

The integral in spherical coordinates is: 02π0π074ρ6sinϕdρdϕdθ\int_{0}^{2\pi} \int_{0}^{\pi} \int_{0}^{7} -4\rho^6 \sin\phi \, d\rho \, d\phi \, d\theta


Would you like me to clarify any step? Here are five questions to consider:

  1. Would you like a step-by-step explanation of the coordinate transformation rules?
  2. Should I elaborate on the calculation of volume elements?
  3. Do you need further clarification on the bounds in spherical coordinates?
  4. Would you like examples of converting other integrals to spherical coordinates?
  5. Do you need help visualizing this region geometrically?

Tip: When converting integrals to spherical coordinates, ensure that the symmetry of the region is fully utilized to simplify bounds and computations.

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Math Problem Analysis

Mathematical Concepts

Coordinate Transformation
Spherical Coordinates
Multivariable Calculus

Formulas

x = ρ sinφ cosθ
y = ρ sinφ sinθ
z = ρ cosφ
x² + y² + z² = ρ²
Volume element: dV = ρ² sinφ dρ dφ dθ

Theorems

Pythagorean Theorem (for deriving spherical relationships)

Suitable Grade Level

Undergraduate - Multivariable Calculus