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Homework Help: Physics 100 homework help

  1. Sep 6, 2007 #1
    I have a homework problem that I cant solve, I have been spending some time on it. It goes like this...

    An automobile traveling 95km/ overtakes a 1.10 km long train traveling i the same direction on a track parallel to the road. If the train's speed is 75kh/h how long does it take for the car to pass it, and how far will the care have traveled in this time?
  2. jcsd
  3. Sep 6, 2007 #2
    you must show your work, first.

    try considering this question:
    An automobile travelling 95 km/hr is 1.10 km behind a train(a point source) that is travelling at 75 km/hr, and so how long does it takes...?
  4. Sep 6, 2007 #3


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    always draw a diagram if in doubt
  5. Sep 6, 2007 #4
    remember that all motion is relative so think of the way the car is moving relative to the train, so how long would it take?
  6. Sep 7, 2007 #5


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    by the way, with that sort of speed, I don't think it is a question involving special relativity either, so standard newtonian mechanics and Galilean relativity are applicable
  7. Sep 8, 2007 #6


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    Denote the position of the front part of the train as y


    Denote the position of the car as


    You can see the logic of the equations above, at time t = 0, y=1.10km (correct!)
    At time t=0, x=0(correct)

    with the derived equations of the positions of the train and car, and for the car to overtake the train, their position have to be the same at a certain time t, so, what should you do???
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