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Homework Help: Locomotive Force

  1. Sep 15, 2010 #1
    1. The problem statement, all variables and given/known data
    A locomotive is pulling 15 freight cars, each of which is loaded with roughly the same weight. The mass of each can be taken to be 37,000 kg. If the train is accelerating at 0.72 m/s^2 on a level track, what is the tension in the coupling between the second and third cars? The car nearest the locomotive is counted as the first.

    2. Relevant equations

    3. The attempt at a solution
    I used F=ma to find that 37,000 kg * 0.72 m/s^2 = 26640 N. I know that this is the force for each traincar, I just don't know what to do with it.
  2. jcsd
  3. Sep 15, 2010 #2
    Nevermind, I figured it out.

    Since we are looking at the tension between the second and third cars, we only have to look at the force of 13 cars. You simply have to multiply the weight of one car by 13 and use the equation F=ma to calculate:

    F = (13)(37,000kg)(.72m/s^2)

    F= 346,320 N
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