Homework Help: Electrostatic and Gravitational Forces

1. Jun 5, 2007

grscott_2000

*Thanks for the help*

Last edited: Jun 6, 2007
2. Jun 5, 2007

Staff: Mentor

Hint: Call the distance "D". Maybe you don't need the actual distance.

That's the one.
No, that's the weight of the particles--their attraction to the earth, not to each other.

3. Jun 5, 2007

grscott_2000

*thanks for the help*

Last edited: Jun 6, 2007
4. Jun 5, 2007

Staff: Mentor

Just set Fel = Fgrav.
Get rid of that minus sign--you are comparing magnitudes.

You are almost there. Clean up the q & Q, m & M stuff: the charges are equal; the masses are equal (and given). Solve for the charge then plug in the numbers.

5. Jun 5, 2007

grscott_2000

*thanks for the help*

Last edited: Jun 6, 2007
6. Jun 5, 2007

Staff: Mentor

Looks good to me.

7. Jun 5, 2007

grscott_2000

Many thanks for your help.... All I often need is a prod in the right direction