Find the Radius of a Cylinder Inside a Hemisphere with Multiple Integration

In summary, the speaker is asking if it is possible to use multiple integration to find the radius of a cylinder that can fit inside a hemisphere with a radius of 4, so that the volume inside the hemisphere and outside the cylinder is 1/12 of the hemisphere's volume. They are initially considering using polar coordinates, but are unsure how to account for the height of the cylinder. Another person suggests using r as the radius of the cylinder and finding its height in terms of r, then using simple algebra to solve for the radius that satisfies the given criterion.
  • #1
nas
1
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if i have a hemisphere of radius 4, is it possible using multiple integration for me to find the radius of a cylinder that sits inside the hemisphere such that the vol inside the hemisphere and outside the cylinder is a 1/12 of the vol of the hemisphere
anyone that can help me on this-i respect you
my inital thoughts were do i do this via polar cordinates-but the hgt of the cylinder is causing me problems-or do i assume hgt is also the radius of the cylinder?
 
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  • #2
I suppose so, but it seems very unneccesary.

let r be the radius of the cylinder - find it's height in terms of r (it touches the surface of the sphere presumably) You can now find the volume of the cylinder in terms of r. Find the r that satisfies the criterion you gave using simple algebra (you know the volume of the sphere too).
 
  • #3


Yes, it is possible to find the radius of a cylinder inside a hemisphere using multiple integration. This can be done by setting up a triple integral, where the innermost integral represents the radius of the cylinder, the middle integral represents the height of the cylinder, and the outermost integral represents the angle of rotation (using polar coordinates).

To solve for the radius of the cylinder, you would first need to find the volume of the hemisphere using a single integral. Then, you can set up the triple integral and use the given information of the volume of the hemisphere and the desired volume of the space between the cylinder and the hemisphere to solve for the radius of the cylinder.

It is important to note that the height of the cylinder may not necessarily be the same as the radius of the hemisphere. You may need to use a variable for the height and solve for it along with the radius of the cylinder.

I would also recommend consulting with a math tutor or professor for guidance on setting up the triple integral and solving for the radius of the cylinder. Best of luck!
 

Related to Find the Radius of a Cylinder Inside a Hemisphere with Multiple Integration

1. How do you find the radius of a cylinder inside a hemisphere using multiple integration?

To find the radius of a cylinder inside a hemisphere using multiple integration, you will need to set up a triple integral. This involves integrating over the volume of the cylinder, which is bounded by the hemisphere and two planes perpendicular to the base of the cylinder. The limits of integration will depend on the given dimensions of the hemisphere and cylinder.

2. What is the formula for calculating the volume of a cylinder inside a hemisphere?

The formula for calculating the volume of a cylinder inside a hemisphere is V = πr2h + 2/3πr3, where r is the radius of the cylinder and h is its height. This formula takes into account the volume of the cylinder and the volume of the spherical cap of the hemisphere that is inside the cylinder.

3. How does the radius of the cylinder affect the volume of the hemisphere?

The radius of the cylinder will directly affect the volume of the hemisphere. As the radius of the cylinder increases, the volume of the hemisphere will decrease. This is because the cylinder takes up more space inside the hemisphere, leaving less room for the spherical cap that makes up the rest of the hemisphere's volume.

4. Can you use a single integral to find the radius of a cylinder inside a hemisphere?

No, a single integral is not sufficient to find the radius of a cylinder inside a hemisphere. The volume of the cylinder is determined by its height and radius, while the volume of the hemisphere is determined by its radius alone. Therefore, a triple integral is necessary to take into account both the volume of the cylinder and the hemisphere.

5. How can this concept of multiple integration be applied in real-world situations?

The concept of multiple integration, specifically finding the radius of a cylinder inside a hemisphere, has real-world applications in fields such as architecture and engineering. For example, it can be used to determine the dimensions of a storage tank or the volume of a water tower, which both involve a cylindrical shape inside a hemispherical shape. It can also be applied in physics and astronomy to calculate the volume of objects such as planets and moons.

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