How do you find the volume of a solid of revolution using integration?

In summary, the problem involves finding the volume of a solid that is rotated around the y-axis, with a given equation x=2y^2 and limits of y=+-6. The correct approach is to use the integral 2pi*x(f(x)dx, which can be rewritten as integral from -6 to 6 of 2pi*y*2y^2 dy. By finding the radius of each circular cross section and plugging it into the area formula for a circle, the volume can be calculated.
  • #1
pugtm
18
0

Homework Statement



x=2y^2
x=0
y=+-6
rotated around y

Homework Equations


integral 2pi*x(f(x)dx

The Attempt at a Solution



integral from -6 to 6 of 2pi*y*2y^2 dy
but i get something far less than the correct answer
 
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  • #2
What are all the * symbols supposed to mean? Multiplication?

Just think of this as Area times length. Since it's rotation around the y-axis you can see that it's easiest to differentiate with respect to y. It's going to make a bunch of little circles. What is the radius of those? (your function?).

From there, you need to plug it into the area of a circle to get pi(radius)^2
So if the volume of the solid is area times width, and in the integration dy is the width, what integral would solve this problem?
 

Related to How do you find the volume of a solid of revolution using integration?

1. What is a solid of revolution problem?

A solid of revolution problem is a type of mathematical problem that involves rotating a two-dimensional shape around an axis to create a three-dimensional object. This is also known as a "revolved volume" or "solid of revolution".

2. What is the purpose of solving a solid of revolution problem?

The purpose of solving a solid of revolution problem is to calculate the volume, surface area, and other properties of the resulting three-dimensional object. This is useful in many fields such as engineering, physics, and geometry.

3. What are the steps to solve a solid of revolution problem?

The steps to solve a solid of revolution problem are: 1. Identify the shape being rotated and the axis of rotation. 2. Set up the integral to find the volume or surface area of the object. 3. Evaluate the integral using appropriate integration techniques. 4. Simplify the solution and include units if necessary.

4. What are some common shapes used in solid of revolution problems?

Some common shapes used in solid of revolution problems are circles, rectangles, and triangles. However, any two-dimensional shape can be used as long as it can be rotated around an axis.

5. How does the radius of rotation affect the resulting solid in a solid of revolution problem?

The radius of rotation determines the size of the resulting solid. A larger radius will create a larger solid, while a smaller radius will create a smaller solid. Additionally, the radius can affect the shape of the resulting solid, with larger radii creating more rounded shapes and smaller radii creating more elongated shapes.

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