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: Electrostatic algebra

  1. Feb 3, 2010 #1
    1. The problem statement, all variables and given/known data

    I have a homework question on electrostatic seesaws. My problem is the algebra.

    2. Relevant equations

    I have been following another example and any guidance to help me proceed would be great.

    0= (2q Q)/(4πε_o r²)+(q Q)/(4πε_o r²)-m
    0= (3q Q)/(4πε_o r²)-m
    m=(3q Q)/(4πε_o r²)

    I don't understand line 2. I don't understand how part of the equation has cancelled out. I know there is a step missing so could anyone point me in the right direction.

    3. The attempt at a solution
     
  2. jcsd
  3. Feb 3, 2010 #2

    CompuChip

    User Avatar
    Science Advisor
    Homework Helper

    There is no step missing.

    There are two fractions which are the same, therefore they can be added:
    [tex]\frac{2x}{y} + \frac{x}{y} = \frac{3x}{y}[/tex]
     
  4. Feb 3, 2010 #3
    Of course! Thank you compuchip x
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook