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Man pulling railroad cars

  1. Apr 30, 2015 #1
    1. The problem statement, all variables and given/known data
    In April 1974, John Massis of Belgium managed to move two passenger railroad cars. He did so by clamping his teeth down on a bit that was attached to the cars with a rope and then leaning backward while pressing his feet against the railway ties. The cars together weighed 700 kN (about 71 tons). Assume that he pulled with a constant force that was 2.5 times his body weight, at an upward angle θ of 33˚ from the horizontal. His mass was 79 kg, and he moved the cars by 3 m. Neglecting any retarding force from the wheel rotation, find the speed of the cars at the end of the pull.

    2. Relevant equations

    Fnet = Acceleration * Mass

    ax = Fcos(theta)/ M
    3. The attempt at a solution
    I have absolutely NO idea what to do. The professor didn't go over any problems like this DX Help!!!
  2. jcsd
  3. Apr 30, 2015 #2

    Simon Bridge

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    So you have never seen any problems involving a mass being accelerated by a force?
  4. Apr 30, 2015 #3
    No D:

    I tried the formula but couldn't find acceleration
  5. Apr 30, 2015 #4

    Simon Bridge

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    Try drawing a free body diagram for the situation - what are the forces on the train?
    Please show your best attempt so far.
  6. Apr 30, 2015 #5


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    And, like trying to solve this problem of yours:


    you'll also need to resolve some forces into their components.

    I can't comment on the quality of your instruction in this subject, but it seems you are lacking knowledge of some very basic concepts in simple vector mechanics. :frown:
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