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Homework Help: 2 Vectors with Angles acting on an object

  1. Oct 25, 2012 #1
    Hey guys, I am having a little trouble determining the final answer to this question.

    Basically an object is being pulled by two forces and I am suppose to find the Net Force

    F1 = 12 N at an angle of 32 degrees (upwards)
    F2 = 15 N at an angle of 24 degrees (downwards)

    So what I did was split the two vectors and try to find Fnetx and Fnet y

    For Fnetx = F1net + F2net

    F1 = 12Cos(32)
    F2 = 15 cos(24)

    I added F1x and F2y and got
    Fnetx = 23.87 N

    For Fnety

    F1y = 12sin32 = 6.36 N
    F2y = 15sin24 = 6.10 N

    I subtracted F1y-F2y because F2y is going in the negative direction so
    Fnety = 0.26 N

    I am not sure if I should add these together or use PT to get Fnet....then use Trig ratios to get the angle.... ?

    Any ideas? I appreciate the help!
  2. jcsd
  3. Oct 25, 2012 #2
    You've now got the x and y components of a vector.
    So how do you calculate the length and direction of the vector from them?

    (You can't just add the lengths of the components - that would make no sense.)
  4. Oct 25, 2012 #3
    If I have Fnetx and Fnety

    Would I use pythegorean theorem to find Fnet, and then Trig ratio to get the angle?
  5. Oct 25, 2012 #4
    Exactly that.
  6. Oct 25, 2012 #5

    Okay perfect However could you please explain why I would not substract the F1y by the F2y?

    Because F2y is a downward motion, it would not be negative?
  7. Oct 25, 2012 #6
    You do subtract them; everything you have done up to this point is correct.
  8. Oct 25, 2012 #7
    Okay its just that the answer doesnt seem correct to me.

    Fnetx = 23.87 N

    Fnety = 0.26 N

    Using PT:

    Fnet = 23.87 N

    Then then using Trig Ratios, the Angle = 0.62 degrees...... which doesnt seem correct..?
  9. Oct 25, 2012 #8


    User Avatar

    Staff: Mentor

    This thread has been moved to the "Introductory Physics" section of "Homework & Coursework Questions", where it should have been posted in the first place. Carry on, and try to remember to post similar questions here in the future. :smile:
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