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Homework Help: Newton's second condition of equilibrium

  1. Oct 19, 2005 #1
    here's the question as written:

    A person is attempting to pull a large stone wheel up a step. The wheel has a mass of 300kg. Assuming the force the person applies is horizontal and at the certer of gravity, what imust the force be to start the wheel rolling over the curb?

    alright, so i found the weight of the wheel, 2940N, the pivot poing is going to be at the corner of the step, and the angle created between where the wheel hits the ground and the pivot point to be 16.7degrees. i have no clue as to what direction to go in next, can anyone help?
  2. jcsd
  3. Oct 19, 2005 #2
    Is the 16.7 deg angle given, because, as you wrote it theres no way to find that angle..

    However, a normal reaction force directed away from the point of contact will be the force responsible for moving the wheel up the step, and the normal force is dependant on the force of the person. Break that normal force vector into components.
  4. Oct 19, 2005 #3
    the angles not given but i derrived it

    the diameter of the wheel is 1m and the height of the step is .15m
    so using the radius of the wheel, the heigt of the step and the defination of the tangent function i got 16.7degrees
  5. Oct 19, 2005 #4
    Well you implied that you gave us all the information given. That is the correct angle though.
  6. Oct 19, 2005 #5
    sorry, it was in the picture and i forgot to type it in
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