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Homework Help: What is the tension in the coupling

  1. Nov 12, 2006 #1
    An inter city Express locomotive pulls 14 cars, each with a mass of 53,000 kg. What is the tension in the coupling between the thrid and fourth cars when the acceleration of the train is 0.26m/s.

    ok so im looking for T.
    53000(0.26) = T?
    i dont think this is correct because they mentioned 3,4 cars
    or was that just random?

    I dont know at all.

    a) What is the minimum time in which one can hoist a 1.00-kg rock height of 10.0m if the string used to pull the rock up has a breaking strength of 10.8 N? Assume the rock to be initially at rest.
    b) If the string is replaced by one that is 50% stronger, by what percentage will the minimum time for the hoist be reduced.

    alright a) i just used a= 2(x-xo)/t^2 and then i got 2(10)/t^2 = 10.8/1
    so i got 10.8=20/t^2 and so t would be root 10.8 but the answer is 4.5s... why??

    b) i need to get a) to solve this...
    Last edited: Nov 12, 2006
  2. jcsd
  3. Nov 12, 2006 #2


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    Homework Helper

    Don't you have an idea about the whole system?

    Your whole system is 14 cars, being pulled by a train with an acceleration of 0.26 m/s^2. Think about the problem of the 3 blocks (between each block there's a string) being pulled by a force F.
  4. Nov 13, 2006 #3
    so there is T1 T2 and T3 and i have to find T3.
    isnt T3
    F= (m1+m2+m3).26
    so it would be 3(53000)(0.26) = T?
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