please, i really have to get this right! thanx.?

Question

please help with this! it's urgent!

question: calculate the magnitude of the repulsive force between a pair of like charges, each one of micro coulomb, separated by a distance of one centimeter.

Answer 1

I'll tell you what...I'll give you the equation and you can fill in the blanks, ok? I wont do ALL the work for you :)

to get the magnitude:

F = k_c((q_1)(q_2)/r^2)

so
F = the magnitude
k_c (K sub c) = Coulomb Force Constant which is equal to 8.988×10^9 N m^2 C^-2
q_1 (Q sub 1) = charge on one body
q_2 (Q sub 2) = charge on the other body
r = distance

Multiply q_1 by q_2 first, then divide that by the distance squared (r^2). Then multiply that result by the Coulomb Force Constant, 8.988×109 N m^2 C^-2, remember to cancel units and such, and thats your answer.

This is what is known as the scalar version of Coulomb's Law. further info below if needed.

to the poster above: sigh, it is a homework problem, and if you think it is, dont give the answer. I think by pointing people in the right direction and making it as easy as possible to understand, hopefully they can do it themselves, which means they might actually learn something!
I dont think the point of this place is to do peoples homework, i'd rather think its a place that someone can learn something, but it doesnt help when answers are dropped everywhere. anyway, sorry, didnt mean to get on my soapbox :)

Answer 2

The interaction force between two charges is given by
-1/(4*pi*epsilon_0) *q_1 *q_2/r^2
with the constant 1/(4*pi*epsilon_0) being about 9*10^9.

Plug in the numbers you have, and you get 90N.

BTW, this sounds like a question you got from school as a homework.