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Homework Help: Finding velocity components with Forces?

  1. Feb 2, 2014 #1
    Three forces acting on an object are given by F1 = (−1.85i+ 6.35j) N, F2 = (4.90i − 1.15j) N, and F3 = (−44.5i) N. The object experiences an acceleration of magnitude 3.55 m/s2.

    They want the velocity components of the object after 4 seconds.

    First, I calculated the direction of the acceleration to be 169.74 degrees, which it says is correct.

    So, I went and calculated its speed after 14 seconds, and I got 49.7 m/s and it says its right.

    Then, I went and and calculated vx=49.7*cos(169.74) and got it right.

    However, when I go to calculate vy=49.7*sin(169.74), it says its wrong but "I calculated the y component correctly using my incorrect values from above". Yet I got all of the above information right...can anyone help if I'm doing something wrong when calculating vy?

  2. jcsd
  3. Feb 2, 2014 #2


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    Gold Member

    maybe you try inputing 49.7*sin(10.26).
  4. Feb 2, 2014 #3


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    Homework Helper
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    Check the math .... I don't get the same angle you calculated. Or apparently what the answer key has calculated. Maybe you wrote it down wrong? Please show your work.
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