A volume integral over a sphere

In summary, a volume integral over a sphere is a mathematical calculation used to determine the total volume of a three-dimensional object enclosed by a spherical surface. It involves breaking down the sphere into smaller elements and summing their contributions to find the total volume. This integral has applications in various fields such as physics, engineering, and mathematics, and it is different from other types of integrals as it integrates over a three-dimensional surface. While it can be used to find the volume of irregularly shaped objects, other techniques may be more efficient or accurate in certain cases.
  • #1
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Homework Statement



∫∫∫∇.Fdv over x2+y2+z2≤25

F= (x2+y2+z2)(xi+yj+zk)

Homework Equations



∫∫∫∇.Fdv = ∫∫ F.n dσ

n=∇g/|∇g|

The Attempt at a Solution



g(x,y,z)=x2+y2+z2-25

taking the surface integral and replacing all
(x2+y2+z2) with 25
i got
125 * ∫∫ dσ = 12500π

But the answer key says it is 100π
I think i am making a mistake with numbers but, i couldn't find what is wrong.

Thanks
 
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  • #2
I don't think anything is wrong except the answer key.
 
  • #3
Hmm, ok then, thanks.
 

1. What is a volume integral over a sphere?

A volume integral over a sphere is a mathematical calculation that determines the total volume of a three-dimensional object that is enclosed by a spherical surface. It is used in various fields of science, such as physics, engineering, and mathematics.

2. How is a volume integral over a sphere calculated?

The volume integral over a sphere is calculated by integrating the function representing the object's volume over the entire surface of the sphere. This involves breaking down the sphere into smaller, infinitesimal elements and summing up the contributions from each element to get the total volume.

3. What are the applications of a volume integral over a sphere?

A volume integral over a sphere has various applications in fields such as electromagnetism, fluid mechanics, and thermodynamics. It is used to calculate the volume of a three-dimensional object with a spherical shape, which can then be used to find properties such as mass, density, and moment of inertia.

4. How is a volume integral over a sphere different from other types of integrals?

A volume integral over a sphere is different from other types of integrals because it involves integrating over a three-dimensional surface instead of a two-dimensional plane. This adds another level of complexity to the calculation and requires the use of specialized techniques, such as spherical coordinates.

5. Can a volume integral over a sphere be used to find the volume of irregularly shaped objects?

Yes, a volume integral over a sphere can be used to find the volume of irregularly shaped objects. This is because the sphere can be used as a "bounding surface" for the object, enclosing it completely and allowing for the calculation of its total volume. However, this method may not always be the most efficient or accurate, and other techniques may be used in certain cases.

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