Calculating Gravitational Energy

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Discussion Overview

The discussion revolves around the calculation of gravitational energy, specifically examining an equation derived from multiplying angular acceleration by the surface area of a sphere. Participants explore whether this equation accurately describes gravitational energy and its implications in planetary motion.

Discussion Character

  • Technical explanation, Debate/contested, Mathematical reasoning

Main Points Raised

  • One participant proposes that multiplying angular acceleration by the surface area of a sphere yields an equation for energy, questioning its meaning and whether it describes gravitational energy.
  • Another participant requests the specific equations and context in which they were applied to better understand the claim.
  • A different participant asserts that the dimensional analysis of the equation is correct, suggesting it aligns with the dimensions of energy.
  • Further clarification is provided that the equation involves angular velocity and surface area, leading to a dimensional formula that matches energy.
  • One participant argues that having dimensions of energy does not necessarily imply that the quantity represents energy, using torque as an example.
  • Another participant challenges the initial claim by stating that if the surface area is truly massless, the equation would not yield a mass dimension, and suggests that the equation may represent work done to accelerate a thin spherical shell instead.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of the equation and its implications for energy, with no consensus reached regarding whether it accurately describes gravitational energy.

Contextual Notes

There are unresolved assumptions regarding the mass of the spherical shell and the definitions of terms used in the equations, which may affect the validity of the claims made.

Bravodhan
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When I multiplied angular accelaration with surface area of sphere .I got an equation for energy.

What do this equation mean by?
Is this equation describe gravitational energy?
 
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Can you post the equations you used and the problem they were used in?
 
But dimensionally this equation is correct.
 
Angular accelaration*surface area of a sphere = Energy
Angular velocity/time*4(pi)r2=Energy

Dimensional formula:-
M0 L0 T-2 * M L2 T0 = M L2 T-2

M L2 T-2 = Energy

I take this energy equation in terms of planetry motion .
 
Last edited:
The fact that something has dimensions of energy doesn't make it an energy. Torque, for example.
 
First, if its truly surface area, you get M0 not M. The whole equation is massless.
The way you have written it, it is the mass of a thin spherical shell times the angular acceleration.

Second, Work also has the dimensions of Energy. I think your equation gives you the amount of work expended to accelerate (spin up or spin down) the thin spherical shell by that much.

Jim Graber
 

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