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Homework Help: Dynamics hay bales Problem

  1. Mar 30, 2005 #1
    Hey!
    I have a physics problem on dynamics. I did the question and received an answer, however, the answer is different from the one that i was given. I just want to know if I did something wrong (i probably did) or if the answer that was given is wrong. here it goes:

    Proper storage of hay bales is essential for the survival of cattle during Canadian winters. A farmer uses a cable to exert an upward pull of 850N on a 81.6kg bale of hay at a local farm. Use a diagram and determine the acceleration of the bale as it is lifted onto a barn loft.
    The answer that is given is 0.607m/s^2

    Here's how I executed the problem:
    a) drew a FBD diagram
    ^
    l
    l
    l T=850N
    O
    l
    \/ Fg

    b) i found the force of support on the bale of hay (not sure if this is right)
    F=ma
    = 81.6kg x 9.81m/s^2
    = 800N

    c) subtracted this force from the tension force:
    850N-800N= 50N

    d) i used the formula again F=ma

    a=F/m= 50N/81.6kg
    = 0.613m/s^2
     
  2. jcsd
  3. Mar 30, 2005 #2
    Considering you are off by 0.06m/s^2 I would say your error is from rounding.

    In part b) 81.6 x 9.81 = 800.496

    850 - 800.496 = 49.504

    49.504/81.6 = 0.606666666m/s^2
     
  4. Mar 31, 2005 #3
    alright! good to know that i'm on the right track :biggrin:
    Thx for the help!

    jen
     
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