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Kinematics Problem

  1. Sep 15, 2004 #1
    Hello everyone, this problem may seem simple to all of you, but I seem to be having a mental block. My physics prof assigned some review last class and I seem to be stuck on this problem.

    Here goes:
    When a high speed train traveling at 161km/h rounds a bend, the engineer see that there is a locomotive lying on the track directly ahead of the moving train. The locomotive is traveling at 29.0km/h in the same direction as the train, and is 676m away when the train sees it. The engineer of the high speed trian imeediatelly applyes the brakes.
    (a) that must be the decelleration of the train in order not to hit the locomotive. (friction is neglected).

    Ive tried setting distance traveled of the two events equal to eachother, and I keep getting a decelleration of -1.43m/s^2, but the answer is 0.93m/s^2. A helpfull hint on how to approach the problem would be fantastic.
    Awaiting a reply, Thanks.
  2. jcsd
  3. Sep 15, 2004 #2
    First of all, your answer your answer for a will be negative, but the answer to the question should be positive because they ask for the decelleration.

    If they are traveling in the same direction, the speed of the train with respect to the locomotive is ____ (pretent the locomotive is stationary). The distance is 676 m. What kinematics formula applies to this? Now solve for a.
  4. Sep 15, 2004 #3
    thanx man.
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