# Find the ratio of the electrostatic force

1. Jul 5, 2010

### atoreta88

This is the problem:
"Determine the ratio of the electrostatic force to the gravitational force between a proton and an electron, FE/FG. Furthermore, note the mass of an electron is 9.109 x 10^-31 kg and the mass of a proton is 1.672x10^-27 kg.G and K are constants."

I'm not exactly sure what formulas to use and what to plug in. thanks for the help! ^_^

Last edited: Jul 5, 2010
2. Jul 5, 2010

### Tusike

Well, you only need to use two formulas. What is Coulomb's law for the force between two charges? And what is Newton's law for the force of gravity between two masses? I suppose they ought've taught you that, otherwise you wouldn't be given a problem like this.
Also, the problem should state that the elemental charge is 1.6*10^-19C.

3. Jul 5, 2010

### Redbelly98

Staff Emeritus
I would say that the textbook should state this somewhere, in which case it's not necessary to state it in every problem that involves protons or electrons. Sometimes a student is expected to look things up. Quite likely, the value is given in the inside front or back cover, as well as somewhere in the chapter this problem came from.

4. Jul 6, 2010

### Tusike

Well, it gave the mass of the proton and electron... I just thought that the elemental charge falls in the same category as those do, but I might be wrong. What you said can be applied to the masses as well, a student should be able to look them up too.

5. Jul 6, 2010

### Redbelly98

Staff Emeritus
Good point.

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