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Homework Help: Find the magnitude even though direction is correct?

  1. Sep 7, 2010 #1
    1. The problem statement, all variables and given/known data

    The force exerted by the wind on the sails of a sailboat is 490 N north. The water exerts a force of 250 N east. If the boat (including its crew) has a mass of 250 kg, what are the magnitude and direction of its acceleration?

    2. Relevant equations

    V= SQRT(X2+Y2)

    3. The attempt at a solution

    Drew it out on a piece of paper:
    (0, 490N)
    (250, 0)
    So: (250, 490)

    Direction = tan-1(490/250) = 62.96

    Magnitude = V = SQRT(490^2+250^2) = 550 = Wrong?
    Why would the magnitude be incorrect? Or can anyone point out where I may be wrong?
    Thank you!

    Edit - The answers are supposed to be in acceleration (m/s^2) and my magnitude came out to be:

    550 Kg m/s^2 so I just divided by the kg and got my answer!
    Silly mistake ;)
    Last edited: Sep 7, 2010
  2. jcsd
  3. Sep 7, 2010 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Welcome to PF. It's always good to see people who pay attention to units!

    Glad things worked out :smile:
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