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Homework Help: Car merging to main road: can it really be so simple?

  1. Oct 11, 2009 #1
    1. The problem statement, all variables and given/known data

    Upon merging from side to main road and starting from rest with a constant acceleration 3 m/s². At the exact time of our merging, another car is driving on the main road in the same direction with speed 50 km/h. At least how far behind us should the car be, if we don’t want it to catch up with us?

    2. Relevant equations

    v^2 = v0^2 + 2as
    s = (v^2 - v0^2) / 2a

    3. The attempt at a solution

    First I converted 50 km/h into 13.89 m/s.
    For initial velocity I took 0, because the car starts from rest. For velocity I took the velocity of the second car, which is 50km/h (13.89m/s).

    After plugging the numbers into the formula s = (v^2 - v0^2) / 2a, a got the result 4.38 m.
    Somehow the distance seems too small?! Were my calculations correct?
  2. jcsd
  3. Oct 11, 2009 #2


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    Science Advisor
    Homework Helper

    I think you made a typo on the caclulator
    s = 13.8^2 / 2*3 = 31.7m
  4. Oct 11, 2009 #3
    Thank you.
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