Let W be part of the solid sphere of radius 4, centered at the origin, that lies above the plane z = 2. Set up an integral in cylindrical coordinates to find the volume of the region. Do NOT actually integrate.

Respuesta :

Answer:

V = ∫∫∫rdrdθdz integrating from z = 2 to z = 4, r = 0 to √(16 - z²) and θ = 0 to 2π

Step-by-step explanation:

Since we have the radius of the sphere R = 4, we have R² = r² + z² where r = radius of cylinder in z-plane and z = height² of cylinder.

So, r = √(R² - z²)

r = √(4² - z²)

r = √(16 - z²)

Since the region is above the plane z = 2, we integrate z from z = 2 to z = R = 4

Our volume integral in cylindrical coordinates is thus

V = ∫∫∫rdrdθdz integrating from z = 2 to z = 4, r = 0 to √(16 - z²) and θ = 0 to 2π

Space

Answer:

[tex]\displaystyle V = \int\limits^{2 \pi}_{0} \int\limits^{2\sqrt{3}}_{0} \int\limits^{\sqrt{16 - r^2}}_2 {r} \, dz \, dr \, d\theta[/tex]

General Formulas and Concepts:

Multivariable Calculus

Cylindrical Coordinate Conversions:

  • [tex]\displaystyle x = r \cos \theta[/tex]
  • [tex]\displaystyle y = r \sin \theta[/tex]
  • [tex]\displaystyle z = z[/tex]
  • [tex]\displaystyle r^2 = x^2 + y^2[/tex]
  • [tex]\displaystyle \tan \theta = \frac{y}{x}[/tex]

Volume Formula [Cylindrical Coordinates]:
[tex]\displaystyle V = \iiint_T \, dV \rightarrow V = \iiint_T {r} \, dz \, dr \, d\theta[/tex]

Step-by-step explanation:

Step 1: Define

Identify given.

Solid sphere w/ radius 4 centered at (0, 0, 0) → x² + y² + z² = 4²

Plane z = 2

Step 2: Find Volume Pt. 1

Find bounds of z.

  1. [Sphere] Substitute in plane z:
    [tex]\displaystyle x^2 + y^2 + 2^2 = 4^2[/tex]
  2. Substitute in cylindrical conversions:
    [tex]\displaystyle (r \cos \theta)^2 + (r \sin \theta)^2 + 2^2 = 4^2[/tex]
  3. Simplify:
    [tex]\displaystyle r^2 + 4 = 16[/tex]
  4. Solve for r:
    [tex]\displaystyle r = 2\sqrt{3}[/tex]

∴ 0 ≤ r ≤ 2√3

Step 2: Find Volume Pt. 2

  1. [Sphere] Substitute in plane z:
    [tex]\displaystyle x^2 + y^2 + 4 = 16[/tex]
  2. Isolate variables:
    [tex]\displaystyle x^2 + y^2 = 12[/tex]
  3. [Unit Circle] Graph [See 2nd Attachment]

∴ 0 ≤ θ ≤ 2π

Step 3: Find Volume Pt. 3

  1. [Sphere] Substitute in cylindrical conversions:
    [tex]\displaystyle (r \cos \theta)^2 + (r \sin \theta)^2 + z^2 = 4^2[/tex]
  2. Simplify:
    [tex]\displaystyle r^2 + z^2 = 4^2[/tex]
  3. Solve for z:
    [tex]\displaystyle z = \sqrt{16 - r^2}[/tex]

∴ 2 ≤ z ≤ √(16 - r²)

Step 4: Find Volume Pt. 4

  1. Substitute in variables [Volume Formula - Cylindrical Coordinates]:
    [tex]\displaystyle V = \int\limits^{2 \pi}_{0} \int\limits^{2\sqrt{3}}_{0} \int\limits^{\sqrt{16 - r^2}}_2 {r} \, dz \, dr \, d\theta[/tex]

∴ the volume of the region is found with the integral above.

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Learn more about multivariable calculus: https://brainly.com/question/17203772

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Topic: Multivariable Calculus

Unit: Triple Integral Applications

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