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Homework Help: Garden cart being pushed over a bump

  1. Mar 7, 2009 #1
    1. The problem statement, all variables and given/known data
    A garden cart loaded with firewood is being pushed horizontally when it encounters a step 8cm high. The mass of the cart and the load is 55kg, and the cart is balanced so that its centre of mass is directly over the axle. The wheel diameter is 60cm. What is the minimum horizontal force that will get the cart up the step.

    2. Relevant equations
    I am guessing the relevant ones are
    [tex]\Sigma F = 0[/tex]
    [tex]\Sigma \tau = 0[/tex]
    because the topic is static equilirium

    3. The attempt at a solution
    No idea on where to even start this one
    Answer in back of book = 500N
  2. jcsd
  3. Mar 7, 2009 #2


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    Homework Helper

    Sketch the circular wheel touching the step. As the wheel begins to go up, the turning point will be its point of contact with the step. If we are going to the right, there will be a moment clockwise due to the horizontal force applied to the wheel barrow. There will be a counterclockwise moment due to the the weight of the wheel barrow. The two moments must be equal for motion to begin.
  4. Mar 9, 2009 #3
    Yes I've got it. Thanks for the tip
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