Changing Charge Distribution and Coulomb's Law

[buoya]

Homework Statement

Two small spheres of charge 10Q each separated by a distance d repel each other with a force F. In terms of F what would be the new repulsive force if 2Q were removed from one sphere and added to the other?

Homework Equations

F = kQq/r^2

The Attempt at a Solution

F = k(10Q)(10Q)/d^2 if 2Q were removed... F = k(12Q)(8Q)/d^2

Is that the answer? it seems too easy

Thanks for any input!

 

[nasu]

You need to find what fraction of F is the new force. Just one more step to do.

 

[dauto]

Your answer is correct but is not "In terms of F". Tip do not use the same symbol "F" to represent two different quantities. If the original force is F than the new force could be any of f, F', F₂, or even G. But it is not F. F is already taken.