1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Relatively simple vectors question, but no numbers...

  1. May 23, 2016 #1
    The unit right now is electrostatics, but this question is really just vectors, nothing to do with charges or anything... anyways here is the info:

    1. The problem statement, all variables and given/known data

    Three identical point charges, A, B, and C are located as shown here:


    The force A-on-C is the same as the force B-on-C. What is the net force on C?

    2. Relevant equations

    I think the only equation I need is the superposition of force principle:
    FnetC = FAonC + FBonC

    3. The attempt at a solution

    Breaking into components (not allowed to use cosine law for some reason):

    I know X-axis force is 0 as the 2 forces cancel out (since they are both equal and in opposite directions).

    FnetCY = FAonC * cos(45) + FBonC * cos(45)

    Not sure what else I can do though...

    EDIT: I messed around with the 1-1-sqrt(2) triangle and I'm not sure if this is right, but is (2/sqrt(2)) * FAonC the right answer?

    EDIT 2: Yes, that's the right answer, but sqrt(2) * FAonC is also right.

    Because guess what, 2 divided by squareroot(2) is THE SAME THING AS squareroot(2)...
    Last edited: May 23, 2016
  2. jcsd
  3. May 23, 2016 #2
    seems okay to me
  4. May 23, 2016 #3
    assuming the charges on the charges on the corners A and B are all the same polarity
  5. May 23, 2016 #4
    Yeah they are all identical.

    How would I use the 1-1-squareroot2 triangle to simplify it more? I'm not sure how to do that part too well.
  6. May 23, 2016 #5
    replace your cos45 statement with the equivalent ratio
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted