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Homework Help: When do i use these kinematic formulas (constant-acceleration)

  1. Sep 18, 2010 #1
    1. The problem statement, all variables and given/known data

    When do i use:


    Compared to...


    What tells me if im going to be using
    (+) or (-)
  2. jcsd
  3. Sep 18, 2010 #2


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    Hi there.
    Note my corrections to your formulae in red. Delta y must have length units. Watch your units!
    Choose a direction as positive, say, positive is upwards. Then negative is downwards. So use plus signs for upward displacement, velocity, and acceleration, and use minus signs for downward displacement, velocity, and acceleration.
  4. Sep 18, 2010 #3
    awesome thank you!
  5. Sep 18, 2010 #4
    Sign Conventions are just a reference. They are not a must condition. Take whatever you like but be sure to use it every time and every where. You should never define sign conventions in two different way in the same equation and to save yourself from confusion you should never change the sign conversion in the whole problem.
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