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Homework Help: Question about forces and acceleration

  1. Oct 30, 2007 #1
    1. The problem statement, all variables and given/known data
    Figure 5-40 shows an overhead view of a lemon half and two of the three horizontal forces that act on it as it is on a frictionless table. Force F1 has a magnitude of 4.40 N and is at theta1 = 30°. Force F2 has a magnitude of 7.00 N and is at theta2 = 30°. The lemon half has mass 0.0300 kg.

    (c) varying velocity v = (13.0t i - 14.0t j) m/s, where t is time in seconds
    2. Relevant equations

    F = MA

    3. The attempt at a solution

    i took the derivative of the velocity to get the acceleration which would be (13.0i + 14.0j)m/(s^2). i then multiply the components of the accleeration with the mass to get the forces of the acclereation. then i added the x component of force 1 and force 2 and a variable x and set it equal to the x component of the acceleration force. am i doing this right cuz i am not gettign the right answer
  2. jcsd
  3. Oct 30, 2007 #2


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    Homework Helper

    Sounds like you have the right idea. But it is difficult to check your work without a picture... one thing.... it's probably just a typo. you wrote acceleration is (13.0i + 14.0j)m/(s^2), but the derivative of:

    v = (13.0t i - 14.0t j) m/s

    is 13.0i - 14.0j not plus...
  4. Oct 30, 2007 #3
    yeah that's what i meant
  5. Oct 30, 2007 #4


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    can you describe the picture and the 3 forces... or better yet post a picture?

    Also can you show your calculations?
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