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Homework Help: Find the acceleration vector of the mass

  1. Sep 19, 2010 #1
    1. The problem statement, all variables and given/known data
    Two forces are acting on a 10.0 kg mass. The forces are:
    F1 = (12.3 x - 13.5 y) newtons where x and y are unit vectors
    F2 = ( -6.30x + 11.9y) newtons

    A) Find the acceleration vector of the mass. Express your answer in unit vector

    2. Relevant equations

    3. The attempt at a solution
    I added the two vectors getting
    (6.0x-1.6y) Newtons then i divided it by the mass to get the acceleration

    So my final answer is a= (0.6x-0.16y) m/s2

    is this correct?
    Last edited: Sep 19, 2010
  2. jcsd
  3. Sep 19, 2010 #2
    Re: Vectors

    You divided each vector (x and y) by ten, meaning that the result was that you were dividing it by ten, twice, resulting in 100.

    Ex: if your vector was 20x + 20y, that magnitude is 400, so dividing each component by 10,
    2x + 2y, you get a magnitude of 4.

    You need to find the magnitude of 6x - 1.6y (Pythagorean) and divide THAT by ten, then use trigonometry to find the x,y components at that magnitude.

    Or, a shortcut is to divide each component by sqrt(10) since the sqrt(10) ^ 2 is 10, so by dividing by the sqrt(10) twice (once to each component) you are ultimately dividing by 10.
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