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Homework Help: HELP! - Kinematics Question

  1. Sep 8, 2010 #1
    I'm having a bit of trouble with this question and would greatly appreciate all the help I can get...

    (a) If the maximum acceleration that is tolerable for passengers in a subway train is 1.54 m/s2 and subway stations are located 816 m apart, what is the maximum speed a subway train can attain between stations? (b) What is the travel time between stations? (c) If a subway train stops for 24.0 s at each station, what is the maximum average speed of the train, from one start-up to the next?

    -I started (a) using the formula: x = vt + 1/2at^2
    -I plugged in 816m for x and 1.54m/s^2 for a
    -I got t=32.5537
    -Then I used this time and the given acceleration to solve for v using the formula: a = v/t getting the answer 50.1326 for part (a)

    Can someone please let me know if this is correct and how I can begin to tackle parts (b) and (c)?

  2. jcsd
  3. Sep 8, 2010 #2


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    Gold Member

    Assuming the train does not slow down when approaching the station , answer looks OK for 'a'.
    For b, you already solved it!
    For c, what's the formula for average speed.
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