Confusion over potential energy equation.

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SUMMARY

The discussion clarifies the confusion surrounding the potential energy equation. The commonly taught equation, PE = MGH, is an approximation valid near the Earth's surface, where M represents mass, G is the gravitational acceleration, and H is the height above the surface. In contrast, the more general equation for gravitational potential energy is derived from the formula GmM/r, which accounts for the gravitational force between two masses. This equation is more accurate for varying distances from a mass, although it is less practical for everyday calculations near the Earth's surface.

PREREQUISITES
  • Understanding of basic physics concepts, particularly gravitational potential energy.
  • Familiarity with the variables in the equations: mass (M), gravitational acceleration (G), height (H), and distance (r).
  • Knowledge of the difference between local approximations and general equations in physics.
  • Basic algebra skills for manipulating equations.
NEXT STEPS
  • Study the derivation of the gravitational potential energy equation GmM/r.
  • Learn about the implications of gravitational potential energy in different contexts, such as celestial mechanics.
  • Explore the concept of gravitational fields and how they affect potential energy calculations.
  • Investigate the limitations of using approximations in physics and when to apply more complex equations.
USEFUL FOR

Students in physics, educators teaching gravitational concepts, and anyone seeking to deepen their understanding of potential energy and gravitational forces.

Kyle Barr
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Hi, I am confused over the potential energy equation. I have been taught that potential energy is MGH M=mass, G=gravity on surface, and H=height from earth. However being on the internet and learning more i have noticed people use GmM/r^2 and i am very confused why it is switched. please help me with my confusion? Thank you. (:
 
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Welcome to PF,
the equation for gravitational potential energy you learned is an approximation that holds close to the surface of the Earth. The other one is more correct in general, though there should be no square on the bottom, but is a pain to use, so we only use it when we have to.
Consider... the word "height" does not make much sense for the distance from a sphere.
 
thank you very much! and i just realized it is + distance, not squared. i got confused with the force of gravity equation.
 

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