Math Problem Statement

Solve this problem

Use the shell method to find the volume of the solid generated by revolving the shaded region about the y-axis.

Solution

To solve this problem, we will use the shell method for revolving the shaded region around the y-axis.

Shell Method Formula:

The volume VV of the solid generated by revolving a region around the y-axis using the shell method is given by: V=2πabxf(x)dxV = 2\pi \int_{a}^{b} x \cdot f(x) \, dx Where:

  • f(x)f(x) is the height of the shell at each value of xx,
  • xx is the radius of the shell,
  • [a,b][a, b] is the interval over which the region is defined.

Step-by-step Solution:

1. Set up the integral

  • The region is defined from x=0x = 0 to x=3x = \sqrt{3}.
  • The function representing the height is given by y=63x2y = 6 - 3x^2.

Thus, the volume is: V=2π03x(63x2)dxV = 2\pi \int_{0}^{\sqrt{3}} x \cdot (6 - 3x^2) \, dx

2. Expand the integrand

V=2π03(6x3x3)dxV = 2\pi \int_{0}^{\sqrt{3}} (6x - 3x^3) \, dx

3. Integrate

Now, integrate term by term: V=2π[6x223x44]03V = 2\pi \left[ \frac{6x^2}{2} - \frac{3x^4}{4} \right]_{0}^{\sqrt{3}} Simplifying the coefficients: V=2π[3x23x44]03V = 2\pi \left[ 3x^2 - \frac{3x^4}{4} \right]_{0}^{\sqrt{3}}

4. Evaluate at the bounds

First, evaluate at x=3x = \sqrt{3}: 3(3)23(3)44=3(3)3(9)4=9274=364274=943(\sqrt{3})^2 - \frac{3(\sqrt{3})^4}{4} = 3(3) - \frac{3(9)}{4} = 9 - \frac{27}{4} = \frac{36}{4} - \frac{27}{4} = \frac{9}{4}

At x=0x = 0, the expression evaluates to 0: 3(0)23(0)44=03(0)^2 - \frac{3(0)^4}{4} = 0

Thus, the volume is: V=2π(94)=9π2V = 2\pi \left( \frac{9}{4} \right) = \frac{9\pi}{2}

Final Answer:

The volume is 9π2\boxed{\frac{9\pi}{2}}.


Would you like a further breakdown of any step?

Here are 5 related questions:

  1. What is the difference between the disk method and the shell method for finding volumes?
  2. How do you decide whether to revolve around the x-axis or y-axis?
  3. What are other real-world applications of the shell method?
  4. Can the shell method be used for solids with holes? How does it work?
  5. How does changing the limits of integration affect the volume calculation?

Tip: Always check the bounds of integration and the axis of revolution to choose the correct method for finding the volume.

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Math Problem Analysis

Mathematical Concepts

Integral Calculus
Volume of Solids of Revolution
Shell Method

Formulas

V = 2π ∫[a, b] x * f(x) dx

Theorems

Method of Shells for Volume of Revolution

Suitable Grade Level

Grades 11-12, College Calculus