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Homework Help: Car Collision Question.

  1. Sep 14, 2005 #1
    I understand that this is a REALLY simple question, but for the life of me, I cannot figure out how to get the right answer.

    "Two cars, A and B, are 400. meters apart. Car A
    travels due east at 30. meters per second on a
    collision course with car B, which travels due
    west at 20. meters per second. How much time
    elapses before the two cars collide?"

    Hopefully, some of you helpful souls out there can help me out. I hope no ridicule comes from this. :(

    What I have done is find out how much time Car A would take to travel 400 M.
    400/30 = 13.333 s

    Now I know that they WILL collide atleast before 13.333 s. Other than that, I'm stuck. Thanks in advance.
  2. jcsd
  3. Sep 14, 2005 #2
    Ah, oh my God. I know why I didn't get the right answer now. I've been putting 20t = 30t. It had never occured to me that 20t + 30t is equal to 400. Damn, I feel stupid now.
  4. Sep 15, 2005 #3


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    Homework Helper

    It happens some time. :smile:
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