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Homework Help: Add forces as vectors help - Thanks!

  1. Dec 6, 2011 #1
    1. The problem statement, all variables and given/known data

    I am not understanding this. This is the question, and the correct solutions for the question I need help with.

    I really dont understand how to get the answer here! Can anyone help me? First steps?

    Question:
    xrm37.jpg


    Answer:

    2l9z61.jpg



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Dec 6, 2011 #2
    Are you confident with the idea that you have 2 forces which are vectors.
    In the first case the vectors (20N and 15N) are at 90 degrees. To find acceleration you divide F by m (5kg) giving 2 acceleration vectors 4 and 3 at 90 degrees.
    You need to find the resultant of these 2 perpendicular vectors (pythagoras !!!)
    In the second case the logic is the same but the angle is not 90 degrees.
    Is this any help?
     
  4. Dec 6, 2011 #3
    I understand how to get (4i + 3j) but how did they eventually come up with 5 m/s^2 at 36.9 degreeS?
     
  5. Dec 6, 2011 #4
    The magnitude of the vector comes from the pythagorean theorem by treating the two vectors as perpendicular sides of a triangle. Trig is the best way to get the angle. How's your trig?
     
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