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Homework Help: Resultant Force: Something I am messing up on in calculation - ?

  1. Jul 7, 2011 #1
    Resultant Force: Something I am messing up on in calculation - ???

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

    Hey all,

    This is a resultant force word problem. I will just post the my answer and the problems answer. I have no idea why there is a different answer here.

    Correct: R^2=1500^2+2300^2 - 2 x 1500 x 2300 Cos(138)
    Correct Answer = R = 3559.2 newton

    My answer is WAYYY off, so there is something I am missing here...

    By the way, I am using the TI-89 Titanium

    Thanks for any help!


    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jul 7, 2011 #2

    berkeman

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    Staff: Mentor

    Re: Resultant Force: Something I am messing up on in calculation - ???

    I get the correct answer just typing it into a cheap ativa scientific calculator.

    Can you say what keystrokes you used to get your incorrect answer? I did something like:

    cos 138 =

    * 2300 =

    * 1500 =

    * -2 =

    + 2300^2 =

    + 1500^2 =

    SQRT =
     
  4. Jul 7, 2011 #3

    SammyS

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    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    Re: Resultant Force: Something I am messing up on in calculation - ???

    Maybe it's TOO much calculator for too SMALL a problem.

    First question: Is you calculator in 'degree' mode, like berkeman's obviously is?
     
  5. Jul 7, 2011 #4
    Re: Resultant Force: Something I am messing up on in calculation - ???

    Thanks both of you.

    I figured it out. Sammy, you were basically right, it was too much of a calc for it. Yes, I was in the wrong mode. PAIN in the butt!

    So, pulled out my dusty Casio calculator and BOOM! solved :)

    Thanks guys
     
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