## Electric Forces

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 !?

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

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

Mentor

## Electric Forces

 Quote by jmatthews1991 I added them

 Quote by berkeman And got the wrong answer...
Yeah I got the wrong answer.. What did I do wrong? What should I do ?

Mentor
 Quote by jmatthews1991 Yeah I got the wrong answer.. What did I do wrong? What should I do ?
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.

 Tags electricty, fields, forces