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Homework Help: Finding the force (complicated)?

  1. Oct 23, 2008 #1
    1. The problem statement, all variables and given/known data
    An object of mass m = 6.70 kg has an acceleration a = (1.17 m/s2)x + (-0.664 m/s2)y. Three forces act on this object: F1, F2, and F3. Given that F1 = (2.71 N)x and F2 = (-1.55 N)x + (2.05 N)y, find F3.
    ( N)x + ( N)y

    2. Relevant equations

    I'll be honest, i have no clue. i know F=ma but have absolutely no clue since there are 3 forces and the x's and y's
  2. jcsd
  3. Oct 23, 2008 #2
    you need to break up all the forces into x and y components. (including mg, normal force) find the net force x and y and use F=ma to find the missing x and y, then add these forces together, (its not just x+y) and that it!
  4. Oct 23, 2008 #3


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    Science Advisor

    Yes, add the forces but I see no reason to assume that "surface of the earth gravitation" should be included. The problem says specifically that there are three forces.
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