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Solid spheres and densities

  • Thread starter etothey
  • Start date
  • #1
22
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Homework Statement


The density of a solid sphere of radius R=10cm and mass M=15kg varies with distance from the center according to the equation p=po*e^(r/R). Determine the constant po.


Homework Equations


density= mass over volume.


The Attempt at a Solution



Change density to mass over volume. Set r = 0. Solve for po and get 3580kg/m3.
Apparantly the equation should be integrated, But I dont understand what the integration would give me?
 

Answers and Replies

  • #2
1,137
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Hi etothey :smile:
(have a rho: ρ)


choose any spherical element of radius x and thickness dx
now write dm for this element in terms of its volume and ρ

integrate this eqn and find total mass M

now use ρ = M/V to find constant rho
 

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