How Do You Calculate Net Force in Coulomb's Law?

[joe98]

Help with coulumbs Law!

Homework Statement

Consider two point charges located on the x axis: one charge, = -10.0 C, is located at = -1.700m ; the second charge, = 30.5C , is at the origin .

What is the net force exerted by these two charges on a third charge = 52.5C placed between and at = -1.055m ?

Your answer may be positive or negative, depending on the direction of the force.

Homework Equations

Coulomb's law

The Attempt at a Solution

first i found,
F(1on3)=k*10*10^-9*30.5*10^-9/.645^2 then,
F(2on3)=k*52.5*10^-9*-10*10^-9/1.055^2

then i added them , but i am gettin the wrong answer d answer shud be -2.43*10^-5 N

can u tell me what's wrong with my working :)

 

[joe98]

the charge is in nC

 

[Clever-Name]

Look at the charges you're using on F(2on3)

 

[joe98]

oh i see thnks :)