Math Problem Statement

Let F = 2xzi - xj - y²k. Evaluate the triple integral of F over the region V bounded by x = 0, y = 0, y = 6, z = x², z = 4.

Solution

The problem asks to evaluate the volume integral of the vector field F over a specified region V. Let's break down the problem:

Given:

  • F = 2xzixjy2k2xzi - xj - y^2k
  • The region V is bounded by:
    • x=0x = 0
    • y=0y = 0
    • y=6y = 6
    • z=x2z = x^2
    • z=4z = 4

You are asked to evaluate the volume integral VFdV\iiint_V F \, dV.

Steps to solve:

  1. Identify the bounds of integration:

    • From the boundaries:
      • xx varies from 0 to 2 (since z=4z = 4 and z=x2z = x^2 implies x=2x = 2).
      • yy varies from 0 to 6.
      • zz varies from x2x^2 to 4.
  2. Decompose the vector field:

    • The integral to evaluate is VFdV\iiint_V F \cdot dV, where the vector field components are integrated accordingly over the volume.
    • You will integrate the components of F in each direction.

Now, for the integral itself:

VFdV=V(2xzdx+(x)dy+(y2)dz)\iiint_V F \, dV = \iiint_V (2xz \, dx + (-x) \, dy + (-y^2) \, dz)

Let's evaluate this integral step-by-step:

First Component (2xz):

0206x242xzdzdydx\int_0^2 \int_0^6 \int_{x^2}^4 2xz \, dz \, dy \, dx The zz-integral yields: x242xzdz=x[z2]x24=x(16x4)\int_{x^2}^4 2xz \, dz = x \left[ z^2 \right]_{x^2}^4 = x(16 - x^4) Thus, the integral becomes: 0206x(16x4)dydx\int_0^2 \int_0^6 x(16 - x^4) \, dy \, dx The yy-integral simply introduces a factor of 6: 602x(16x4)dx6 \int_0^2 x(16 - x^4) \, dx Evaluating this: 6[8x2x66]02=6(32646)=6×1286=1286 \left[ 8x^2 - \frac{x^6}{6} \right]_0^2 = 6 \left( 32 - \frac{64}{6} \right) = 6 \times \frac{128}{6} = 128

Second Component (-x):

0206x24(x)dzdydx\int_0^2 \int_0^6 \int_{x^2}^4 (-x) \, dz \, dy \, dx The zz-integral gives: x[z]x24=x(4x2)-x \left[ z \right]_{x^2}^4 = -x(4 - x^2) Thus, the integral becomes: 0206x(4x2)dydx\int_0^2 \int_0^6 -x(4 - x^2) \, dy \, dx Again, the yy-integral introduces a factor of 6: 602x(4x2)dx6 \int_0^2 -x(4 - x^2) \, dx Evaluating this: 6[2x2+x44]02=6(8+4)=6×4=246 \left[ -2x^2 + \frac{x^4}{4} \right]_0^2 = 6 \left( -8 + 4 \right) = 6 \times -4 = -24

Third Component (-y²):

0206x24(y2)dzdydx\int_0^2 \int_0^6 \int_{x^2}^4 (-y^2) \, dz \, dy \, dx The zz-integral introduces a factor of (4x2)(4 - x^2): (4x2)06y2dy=(4x2)[y33]06=(4x2)×72(4 - x^2) \int_0^6 -y^2 \, dy = (4 - x^2) \left[ -\frac{y^3}{3} \right]_0^6 = (4 - x^2) \times -72 Thus, the integral becomes: 7202(4x2)dx-72 \int_0^2 (4 - x^2) \, dx Evaluating this: 72[4xx33]02=72(883)=72×163=384-72 \left[ 4x - \frac{x^3}{3} \right]_0^2 = -72 \left( 8 - \frac{8}{3} \right) = -72 \times \frac{16}{3} = -384

Final Answer:

Summing the three components: 128+(24)+(384)=280128 + (-24) + (-384) = -280

Thus, the value of the volume integral is 280\boxed{-280}.

Let me know if you'd like further clarification or details on any part of this solution! Here are some related questions you could explore:

  1. How do the limits of integration change if the surfaces are altered?
  2. What is the physical significance of this volume integral in vector calculus?
  3. Can this result be verified using the Divergence Theorem?
  4. How would the problem change if a different vector field was used?
  5. How is the method of cylindrical or spherical coordinates applicable to integrals like this?

Tip: When setting up triple integrals, always sketch the region or carefully analyze the boundaries to avoid errors in setting up the limits of integration.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Vector Calculus
Triple Integral
Vector Fields
Bounded Regions

Formulas

Triple integral of a vector field: ∫∫∫ F dV
Vector field components: 2xzi - xj - y²k

Theorems

Divergence Theorem (optional verification)
Basic properties of integration over volumes

Suitable Grade Level

Undergraduate Calculus III or Advanced Calculus