A question on Shell Theorem

  • #1
anhchangdeptra
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0
Imagine all the mass of the earth is in a shell of a thickness of R(earth)/2. So if the object is inside the shell or outside the shell, I know I can apply the shell theorem to solve the gravitational force acting on it. But, what if the object is IN the shell, in another words R(earth)/2<r<R(earth), how do we calculate the gravitational force?
 

Answers and Replies

  • #2
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so its like you have two shells. The object is outside one shell and inside the other. Apply the shell theorem to each one and what do you get.
 
  • #3
anhchangdeptra
8
0
Oh! So we only care about the smaller shell with radius= R/2. The distance from mass m to the center is r so basically we have the same formula as for an object outside the bigger shell= (GMm)/r^2 (only the r is different is the two cases)?
 
  • #4
Bandersnatch
Science Advisor
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Oh! So we only care about the smaller shell with radius= R/2. The distance from mass m to the center is r so basically we have the same formula as for an object outside the bigger shell= (GMm)/r^2 (only the r is different is the two cases)?
M is also different. After all, you don't care about the part of the shell above the object.
 
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  • #5
anhchangdeptra
8
0
Oh yes! I really forget the M. Thank you very much!
 

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