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Homework Help: A freight train has a mass of 4.5*10^7 kg

  1. Oct 16, 2006 #1
    A freight train has a mass of 4.5*10^7 kg. If the locomotive can exert a constant pull of 15*10^5 N, how long would it take to increase the speed of the train from rest to 85 km/h?

    I know u need to use F=ma but how do i find time
  2. jcsd
  3. Oct 16, 2006 #2
    Think! What are you trying to find by using F=ma? Clue: You do need to use a little kinematics in this qn. If u have acceleration, final velocity and initial velocity, how are you goin to find time?
    Last edited: Oct 16, 2006
  4. Oct 17, 2006 #3
    Also remember to use the correct units, i.e. don't use km/hr.
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