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Homework Help: Linear motion

  1. Oct 2, 2005 #1
    I am stuck on this problem...
    A speeding motorist traveling 120 km/h passes a stationary police officer. The officer immediately begins pursuit at a constant acceleration of 10.2 km/h/s (note the mixed units). How much time will it take for the police officer to reach the speeder, assuming that the speeder maintains a constant speed?
  2. jcsd
  3. Oct 2, 2005 #2


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    Homework Helper

    Do you have any equations of motion you are suppose to use?
  4. Oct 2, 2005 #3
    I know 3 equations of motion, but up until now I have only been looking for one variable or working with only one moving object... I'm not quite sure how to incorporate both moving objects into the equations I have. Could someone possibly lead me toward the process for finding the solution? Thanks.
  5. Oct 2, 2005 #4
    You know the distance will be the same so

    d = vt
    d = 1/2at^2

    You can equate those

    vt = 1/2at^2

    Fix your units and solve.
  6. Oct 2, 2005 #5
    got it!

    thank you so much. :smile:
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