Volumes of solids of revolution

In summary, the problem asks for the volume of the remaining solid after a circle with a radius of (a/2) is bored through the center of a sphere with radius a. The easiest way to solve this is by setting up an xyz-axis system and considering the first quadrant in the xy-axis system. By rotating the function f(x)= sqrt( (a^2)/4 - x^2 ) around the y-axis and integrating from 0 to a/4, the volume of the cylinder within the sphere can be found. Multiplying this by two will give the total volume of the remaining solid.
  • #1
Koey
3
0

Homework Statement


A circle with a radius of (a/2) is bored through the centre of a sphere of radius a. Find the volume of the remaining solid.


Homework Equations





The Attempt at a Solution


I've been trying this for an hour now and I've been trying to find the remaining volume by finding the area of the cylinder bored + the little side bits on each side. I've just been getting really messy answers which aren't close to the actual answer.

Urgently need a hand :)
 
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  • #2
The easiest way to do this is in my opinion:
Set the sphere in the center of an xyz-axis system with the axis of the cilinder the y-axis. (for example)
Now consider just the first quadrant in the xy-axis system.
You should know that you can make a function of the curve you see ( f(x)= sqrt( (a^2)/4 - x^2 ) )

To find the volume of the cylinder inside the sphere you only have to rotate the function around the y-axis while integrating from 0 to a/4. Multiply by two and you have the total volume of the cylinder within the sphere.

I'm sure you will be able to solve it now ;).
Goodluck
 
Last edited:

Related to Volumes of solids of revolution

1. What is a solid of revolution?

A solid of revolution is a 3-dimensional shape formed by rotating a 2-dimensional shape around an axis. This creates a shape with a circular cross-section and a varying radius along the axis of rotation.

2. How do you calculate the volume of a solid of revolution?

The volume of a solid of revolution can be calculated using the formula V = π∫(R(x))^2 dx, where R(x) is the radius of the cross-section at a given x-value and the integral is taken over the range of x-values for the shape.

3. What shapes can be used to create solids of revolution?

Any 2-dimensional shape can be used to create a solid of revolution, as long as it is rotated around an axis. Common shapes used include circles, rectangles, and triangles.

4. Are there any real-world applications for calculating volumes of solids of revolution?

Yes, calculating volumes of solids of revolution is used in various fields such as engineering, architecture, and physics. For example, it can be used to determine the volume of a water tank or the amount of material needed to create a cylindrical pipe.

5. Are there any techniques for simplifying the calculation of volumes of solids of revolution?

One technique is to use the method of cylindrical shells, which involves integrating the surface area of a cylindrical shell formed by slicing the shape into thin vertical strips. Another technique is to use the washer method, which involves subtracting the volume of the hole in the center of the shape from the volume of the larger shape.

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