A simple question regarding spheres and spherical shells

In summary, a sphere is a three-dimensional object with a curved surface and solid interior, while a spherical shell is a hollow sphere with a curved surface and no solid interior. The volume and surface area of a sphere and spherical shell can be calculated using different formulas. Spheres and spherical shells have various real-world applications, such as modeling celestial bodies and atoms, and a spherical shell cannot have a negative radius.
  • #1
LostInToronto
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Moved my question to Intro Physics. Mods feel free to delete.
 
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  • #2
I found the answer online. Apparently

[tex]\sigma=\rho dr'[/tex].

This doesn't really make sense to me. Can anyone clear up why this is so?
 

1. What is the difference between a sphere and a spherical shell?

A sphere is a three-dimensional object with a curved surface that is equidistant from its center point. A spherical shell, on the other hand, is a hollow sphere with a curved surface that is also equidistant from its center point. In other words, a sphere has a solid interior while a spherical shell does not.

2. How do you calculate the volume of a sphere and a spherical shell?

The formula for calculating the volume of a sphere is V = (4/3)πr^3, where r is the radius of the sphere. To calculate the volume of a spherical shell, you would subtract the volume of the inner sphere from the volume of the outer sphere. The formula for the volume of a spherical shell is V = (4/3)π(R^3 - r^3), where R is the outer radius and r is the inner radius.

3. Can a sphere and a spherical shell have the same surface area?

No, a sphere and a spherical shell cannot have the same surface area. The surface area of a sphere is given by the formula A = 4πr^2, while the surface area of a spherical shell is given by the formula A = 4π(R^2 - r^2). Since the radius and the inner and outer radii of a sphere and a spherical shell are different, their surface areas will also be different.

4. How are spheres and spherical shells used in real-world applications?

Spheres and spherical shells have a wide range of applications in various fields. For example, in physics, they are used to model celestial bodies such as planets and stars. In chemistry, they are used to model atoms and molecules. In engineering, they are used in the design of pressure vessels and storage tanks. In medicine, they are used to model cells and viruses. These are just a few examples of the many real-world applications of spheres and spherical shells.

5. Can a spherical shell have a negative radius?

No, a spherical shell cannot have a negative radius. A radius is a distance measurement and cannot be negative. If the inner radius of a spherical shell is larger than the outer radius, it is simply referred to as an "empty shell" rather than a "spherical shell".

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