Electric Forces and Fields questions,

[WGman]

Electric Forces and Fields questions, please help!

1. Charge A and Charge B are 2.2 m apart. Charge A is 1.0 Coulomb, Charge B is 2.0 Coulombs, and Charge C is 2.0 Coulombs and is located between Charges A and B and is in electrostatic equilibrium. How far from Charge A is Charge C?

2. Two equal positive charges, both q= 2.0 x 10^ -6 Coulombs, interact with a third charge, Q= 4.0 x 10^ -6 Coulombs. What is the magnitude of the electric force on Q? (In a coordinate plane, the two "q"s are on the y axis: the first one is .3 meters above the origin and the second one is .3 meters below the origin. Q is located .4 meters right of the origin (on the +x axis). this all makes one triangle, or two right triangles side by side.)




2. E= Electric Force/q Electric Force= Kc x q1xq2/(r^2) E= Kc x q/(r^2) Kc= 8.99 x 10^9



3. I haven't gotten much accomplished besides a picture, I'm completely lost! D:

 

[Delphi51]

Welcome to PF, WGman. It would be nice to see your diagram and work. You could scan it, photograph it or sketch it in a paint program. Upload the jpg file to a service such as photobucket and paste a link in your post here.

Charge C will have two forces on it, one to the left and one to the right so your beginning equation will be
F1 + F2 = 0
Fill in the detailed formula for the electric force in each case. One of the distances will be unknown, say x. The other will be (2.2 - x).

Post your work if you need more help!

 

[WGman]

thanks for your help so far!
so now i have set that up, but how can i rearrange the equation to get x once i plug in the variables? thanks!

and for the second one so far i am splitting the triangle formed into two right triangles, with the legs on the x and y axis. once i find the magnitude of the force not on the axis (using r as the hypotenuse, the distance between q and Q) and using sin and cos to find the components before adding them!

 

[Delphi51]

Your equation will have only the one unknown, x. Solve it as you would any simple equation!

Your plan for the second one sounds good.

It is hard to help when I can't see your work.