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Homework Help: Distance when velocity doubles

  1. Jun 19, 2015 #1
    1. The problem statement, all variables and given/known data
    A certain airport runway of length L allows planes to accelerate
    uniformly from rest to takeoff speed using the full length of
    the runway. Because of newly designed planes, the takeoff
    speed must be doubled, again using the full length of the runway
    and having the same acceleration as before. In terms of L,
    what must be the length of the new runway?

    2. Relevant equations

    Not sure how to evens start.
    3. The attempt at a solution
    in my head i said that the runway would double buy i was wrong.
  2. jcsd
  3. Jun 19, 2015 #2


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    Science Advisor

    If you need double the speed and you have the same acceleration, by what factor must you increase the time interval? That's an easier problem. Can you find a relevant equation?

    Using that answer, what can you conclude about the distance required?
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