Potential energy of a non-uniform density sphere

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SUMMARY

The discussion focuses on calculating the potential energy (W) of a non-uniform density sphere characterized by a density function d=d(r) and a gravitational field o(r) derived from it. The equation for potential energy is established as W=1/2 ∫(from 0 to R)(4πd(r)o(r)r^2dr). The user encountered a discrepancy, finding their calculated W to be twice the expected result, prompting inquiries about the integration process and the interpretation of the problem statement. Key insights include the necessity of treating M(r) as a separate integral and the importance of correctly applying the constants and variables involved.

PREREQUISITES
  • Understanding of gravitational potential energy concepts
  • Familiarity with integral calculus
  • Knowledge of non-uniform density functions
  • Proficiency in applying the principles of gravitational fields
NEXT STEPS
  • Study the derivation of gravitational potential energy for non-uniform density spheres
  • Learn about the application of double integrals in physics problems
  • Explore the implications of density functions in gravitational calculations
  • Review the mathematical constants and their significance in physics, particularly π
USEFUL FOR

Students and educators in physics, particularly those focusing on gravitational theory and potential energy calculations, as well as anyone involved in advanced calculus applications in physical contexts.

Sais
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Homework Statement


Perform potential energy W of a non-uniform density sphere by density d=d(r) and o(r)=dW/dm.

Homework Equations


The answer is W=1/2.integral(from 0 to R)(4x3.14xd(r)xo(r)xr^2xdr).

The Attempt at a Solution


I have solved this by this way:
o(r)=-GM(r)/r;
dW=-[GM(r)d(r)4x3.14xr^2]/r xdr;
assemble o(r) in dW then integrate it. But in the end, i find my W twice the answer. Can u help me explain this? Thanks. Sorry if my english was so bad :p
 
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What does "Perform potential energy W" mean? You cannot perform an energy.
Do you want to calculate the potential from this field?
Do you want to calculate the total gravitational binding energy? <- my guess

x is often used for variables, multiplication is indicated with *.
3.14 should be ##\pi##.

Sais said:
dW=-[GM(r)d(r)4x3.14xr^2]/r xdr
That is possible, but M(r) is an integral on its own so you'll get a double integral that you have to simplify.
 

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