# Physics Questions

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3.Which is stronger, the electrical force between an electron and a proton or the gravitational force between these particles?
-I got that the electrical force between an electron and a proton.

6.Two charges separated by one meter exert 1-N forces on each other. If the charges are pulled to a 3-m separation distance what will the force on each charge be?
-This is one I don't understand, my teacher says its suppose to be a ratio problem.

13.
Atomic physicists ignore the effect of gravity within an atom. To see why, calculate and compare the gravitational and electrical forces between an electron and a proton separated by 10^-10m?
-I got: 1.0162796 x 10^-47 and 7.620497955 x 10^-7

To get the answers I got, I used the mass of the proton and mass of the electron.

21. How does one Coulomb of charge compare to the charge on an electron? How do you think such a large difference arose historically?
-This one I don't understand.

• Physics Questions - ,

3, 13 are correct.
6. The force is prop to 1/r2

if r changes by 3, the factor 1/r2 changes by 1/9 so moving the distance from 1 to 3 reduces the force to 1/9 th what it was.

21. The ampere was defined well before the e value was known.
http://en.wikipedia.org/wiki/Coulomb