Volume of the intersection of two cylinders by polar co-ordinates

In summary, the conversation discusses finding the volume of the intersection of two cylinders using cylindrical coordinates. There is a debate about the upper limit of the dz integration, with one person believing it should be r*cos(theta) while the other argues for sqrt(a^2-r^2*sin(theta)^2). It is clarified that the first limit is only true along the curve where the two cylinders intersect and not everywhere on the surface in the first octant.
  • #1
cybermask
5
0
Volume of the intersection of two cylinders by cylinderical co-ordinates

Homework Statement




find Volume of the intersection of two cylinders by cylindrical co-ordinates


The Attempt at a Solution



IN the attached file I found it's 8(a^3)/3
It should be 16 not 8
 

Attachments

  • volume.pdf
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  • #2
I know that the mistake may be trivial but can anyone give me any comment!1
 
  • #3
Why do you think the upper limit of the dz integration is r*cos(theta)? Don't you have z=sqrt(a^2-y^2)=sqrt(a^2-r^2*sin(theta)^2)?
 
Last edited:
  • #4
Dick said:
Why do you think the upper limit of the dz integration is r*cos(theta)? Don't you have z=sqrt(a^2-y^2)=sqrt(a^2-r^2*sin(theta)^2)?

But in the first octent
x^2 + y^2 = r^2
y^2 + z^2 = r^2

so z=x=rcos(theta)

Isn't it?
 
  • #5
That's only true along the curve where the two cylinders intersect. It's not true everywhere on the surface in the first octant.
 
  • #6
Dick said:
That's only true along the curve where the two cylinders intersect. It's not true everywhere on the surface in the first octant.


Thanks Thanks Thanks
 

Related to Volume of the intersection of two cylinders by polar co-ordinates

1. What is the formula for finding the volume of the intersection of two cylinders using polar coordinates?

The formula for finding the volume of the intersection of two cylinders using polar coordinates is V = ∫θ1θ2r1r2 h(r,θ) dr dθ, where θ1 and θ2 are the limits of integration for the angle θ, r1 and r2 are the limits of integration for the radius r, and h(r,θ) is the height of the intersection at a given point (r,θ).

2. How do you determine the limits of integration for θ and r in the formula for finding the volume of the intersection of two cylinders?

The limits of integration for θ and r can be determined by finding the points of intersection between the two cylinders and using those points to create the boundaries of the integration. These points can be found by setting the equations of the cylinders equal to each other and solving for the values of θ and r.

3. Can the formula for finding the volume of the intersection of two cylinders using polar coordinates be applied to any two cylinders?

Yes, the formula can be applied to any two cylinders as long as they have a circular base and their axes are parallel. However, the integration may be more complex for certain cylinder configurations.

4. How does the volume of the intersection of two cylinders change with the angle of intersection?

The volume of the intersection of two cylinders will vary depending on the angle of intersection. As the angle increases, the volume of the intersection will also increase, reaching its maximum when the two cylinders are perpendicular to each other.

5. What is the significance of calculating the volume of the intersection of two cylinders using polar coordinates?

Calculating the volume of the intersection of two cylinders using polar coordinates is important in various fields of engineering and science. It can be used to determine the capacity of cylindrical tanks or pipes, or to analyze the volume of complex geometric shapes for mathematical or scientific purposes.

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