What is the relationship between electrical and gravitational potential energy?

AI Thread Summary
The discussion focuses on calculating the electrical potential energy (EPE) and gravitational potential energy (GPE) of two protons separated by 1 nm. Participants emphasize that the problem is solvable with the provided information, highlighting that potential energy relates to the work done in separating the objects. They suggest using the formulas for gravitational and electrical forces to compute the respective energies. Additionally, there is a discussion about estimating the mass required for hypothetical particles with the same charge to avoid repulsion. The conversation encourages independent problem-solving while providing guidance on the necessary calculations.
ussrasu
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I have no idea what principles i am supposed to use in this question? Could someone show me how to do this question please? Thanks :smile:

Calculate the electrical potential energy of two protons separated by 1 nm, and compare it with their gravitational potential energy. Estimate how heavy hypothetical particles (with the same charge e) must be in order not to repel each other.
 
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Find the EPE and find the GPE, compare how strong they are. Then find the mass that each proton would need to have so that their gravitational attraction would equal their electromagnetic repulsion.
 
I don't know how to do it - with the small amount of info given? Can someone show me how to work it out please?

Thanks! :smile:
 
You should try doing your own homework.. that problem is very do-able, all the information is given.
 
"potential energy" is equal to the work done in separating the objects.

Imagine one of the protons and calculate the work done in moving the other from a distance of infinity to 1m (I started to say from 0 to infinity but that's the wrong way- the force between them is infinite at 0 distance!).

The work is, of course, \int_{x= \infty}^1 F(x)dx where F(x) is the force at distance x.

For gravity that is F(x)= \frac{-Gm^2}{x^2} and for electrical force that is F(x)= \frac{q^2}{x^2} where m and q are the mass and charge on the proton. (Am I missing a constant in the electrical force formula- this isn't my "area of expertise!)
 
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