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I have thought a simple thing:

consider a system of a planet and its natural satellite revolving around it in a perfectly circular orbit(assumed) and this is happening in an isolated space in some part of universe. Now something just happened at infinity that made the planet and its satellite to lose electrons and they both became a positively charged (up to that much, so that they could repel and also take the two bodies spherical, approximately).

My question is will that satellite still be in the same orbit of that planet?

Well, that's pretty simple question, isn't it?

But i was reading a book Halliday resnick krane. There on page 638, para.6 under "Potential Energy of a System of Charges", it is written (and also we all know this)

if the external agent does positive work in assembling the charges from the infinite separation(opposing the repulsive forces in the process), the total energy calculated using Eq. 28-8 will be positive. The External agent has in effect stored the energy in the system. If the charged are released from their position, they will tend to fly apart, the potential energy will decrease and hence their kinetic energy will increase.

now let us consider the above situation again, the two bodies before becoming a charge particles were held by the gravitational force($F_g$) and the satellite (S) was revolving around the planet (P), so when the bodies S and P become charged, the body S wasn't brought from infinity so no external force was there which could have stored energy in the system in the form of potential energy and further more the body S is revolving in a perfectly circular orbit because of $F_g$ and the motion of S is always perpendicular to the direction of the field of the body P hence S is also not doing any work i.e. it is not storing and energy in the system in the form of Potential energy. So if no potential energy was stored in the system in the form of the potential energy then how could the body S gain kinetic energy and go away from the body P?

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    $\begingroup$ the body S wasn't brought from infinity but the charges were, so S does have electrical potential energy $\endgroup$ – user83548 May 26 '16 at 13:32
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    $\begingroup$ Try to use a descriptive title that describes the question you are asking. $\endgroup$ – DilithiumMatrix May 26 '16 at 14:01
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The orbit will change. To be concrete, lets say that the satellite and planet are illuminated by ultraviolet light for a short period of time, so that some electrons are photoemitted from their surfaces. Make the bodies conducting so that the surface charge spreads out evenly.

The repulsion between the charged bodies acts in the opposite direction of the gravitational force, so the force of attraction between satellite and planet is reduced. But since the satellite was originally held in a circular orbit by gravity, it can no longer be in a circular orbit and will have an elliptical orbit instead. If the orbit is elliptical, that means that sometimes the satellite is closer to the planet and other times it is farther away: There is radial motion.

It requires energy (work) to make the radial motion. Where did this energy come from? It came when you extracted the electrons from the bodies. If you remove an electron from the body, then the body becomes positively charged and you have to do work to bring the electron far from the body. As the body charges up, removing electrons becomes harder and harder requiring more work. This is the energy that ultimately does work on the satellite and changes its orbit.

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