Electrostatic and gravitational potential energy question

[Sigma Rho]

Hi all,

I have a few questions that I'd appreciate some guidance on.

There are two identical dust particles:-
mass 13ug
charge +9.8E-15 C
electrostatic potential energy 8.7E-17 J
gravitational potential energy 1.1E-24 J

The mass is given in the question, the energies I calculated. The part of the question that I am having problems with asks me to comment on these values of energy, with reference to the zero points of each.

Apart from saying that there's a lot more electrostatic potential energy than there is gravitational, and that electrostatic force is much more powerful than gravitational force, I don't really know what else to say. Do I need say more than that?

It then asks for the total potential energy of the system, which I haven't seen mentioned in the textbook (or maybe I just didn't read it properly ). Is this just the algebraic sum of the electrostatic and gravitational energies, or is there something else to consider?

How does this change as the separation of the particles changes? I guess I can work this out once I've mastered the question above.

I'm not looking for actual answers to these, I'd rather work them out for myself, but any guidance would be greatly appreciated.

Thanks in advance.

 

[turin]

... comment on these values of energy, with reference to the zero points of each.

Apart from saying that there's a lot more electrostatic potential energy than there is gravitational, and that electrostatic force is much more powerful than gravitational force, I don't really know what else to say. Do I need say more than that?

I imagine that is exactly the point of the question, so I imagine you have answered appropriately.

It then asks for the total potential energy of the system,
...
Is this just the algebraic sum of the electrostatic and gravitational energies,

As far as I can tell.

 

[M98Ranger]

Hi there,

Firstly, great job on calculating the electrostatic and gravitational potential energies for the given dust particles. It's important to note that these values are relative to their respective zero points.

For electrostatic potential energy, the zero point is when the particles are infinitely far apart. This means that the energy value you calculated is the energy required to bring the particles from infinitely far apart to their current separation distance. As for gravitational potential energy, the zero point is typically set at infinity as well, but it can also be set at the surface of a planet or other massive object. In this case, the value you calculated is the energy required to bring the particles from the surface of the planet to their current separation distance.

In terms of commenting on the values, you can mention the fact that electrostatic potential energy is much greater than gravitational potential energy due to the much stronger electrostatic force. You can also mention that the total potential energy of the system is the sum of the electrostatic and gravitational energies, as you mentioned.

As for how the potential energy changes as the separation of the particles changes, you can think about it in terms of the inverse-square law for both electrostatic and gravitational forces. As the separation distance decreases, the forces increase and therefore the potential energy increases. This is because more work is required to bring the particles closer together against these stronger forces.

I hope this helps and good luck with your further calculations!