Opposite Charges/Poles: What Form of Energy?

[adamg]

A positive and a negatively charged sphere attract each other and their kinetic energy increases. What form was the energy in orginally? Is it from the work done in separating the spheres originally? If so, when the spheres are separated, what form of energy do they gain from the work done in separating them? (Similarily with North and South poles of magnets?) Hope you can help, thanks *adam*

 

[HallsofIvy]

Yes, total energy is conserved. The energy the two spheres had before they started moving is "Potential Energy". You are correct, it is "from the work done in separating the spheres originally?".
It is exactly the same as if you lifted a 1 kg mass 1 meter in the Earth's gravitational field, giving it "mgh"= 9.8 Joules of (potential)energy. If you then drop that mass down 1 meter, all that potential energy is converted into kinetic energy: (1/2)mv²= 9.8 so
v²= 19.6 and v= 4.4 m/s. Exactly the same thing with charged particles or magnets.

 

[Graeme Robinson]

The energy in this scenario is in the form of electrostatic potential energy. This is the energy stored in a system due to the interaction between positive and negative charges. When the positively and negatively charged spheres are brought closer together, the potential energy decreases and the kinetic energy increases as they are attracted to each other. This potential energy was originally obtained from the work done in separating the spheres. When the spheres are separated, the potential energy is converted back into kinetic energy as they move towards each other.

Similarly, with north and south poles of magnets, the energy is in the form of magnetic potential energy. When the poles are brought closer together, the potential energy decreases and the kinetic energy increases as they are attracted to each other. This potential energy is obtained from the work done in separating the poles. When the poles are separated, the potential energy is converted back into kinetic energy as they move towards each other.

In both cases, the energy is in the form of potential energy, which is converted into kinetic energy as the objects move towards each other. This is due to the attractive force between opposite charges or poles. The work done in separating the objects initially stores this potential energy, which is released when the objects are allowed to move towards each other.