Electric Forces

jmatthews1991

1. The problem statement, all variables and given/known data
Three charges, Q1, Q2, and Q3 are located in a straight line. The position of Q2 is 0.323 m to the right of Q1. Q3 is located 0.125 m to the right of Q2
In the above problem, Q1 = 1.37 μC, Q2 = -2.53 μC, and Q3 = 3.43 μC. Calculate the total force on Q2. Give with the plus sign for a force directed to the right.


2. Relevant equations

F=kq1q2 / r^2

3. The attempt at a solution
I used the above formula to find the force for charge 1-2, and charge 2-3, and then added them together. I got the wrong answer.
My answers were: 0.29867 N + 4.99 N = 5.29 N
What am i doing wrong !?

berkeman

Q1 and Q3 are both positive, but on opposite sides. Would their forces add?

jmatthews1991

I added them

berkeman

And got the wrong answer...

jmatthews1991

Yeah I got the wrong answer.. What did I do wrong? What should I do ?

berkeman

The force equation that you wrote in your original post (OP) is actually a vector equation. The forces have both magnitude and direction. You need to take that into account when you sum the forces to get the resultant.