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Homework Help: A motorcycle catches a car after accelerating

  1. Jun 3, 2012 #1
    A motorcycle is following a car that is traveling at constant speed on a straight highway. Initially, the car and the motorcycle are both traveling at the same speed of 22.0 m/s , and the distance between them is 60.0 m . After t1= 5.00 s , the motorcycle starts to accelerate at a rate of 5.00 m/s^2 . The motorcycle catches up with the car at some time .

    How long does it take from the moment when the motorcycle starts to accelerate until it catches up with the car? In other words, find t2-t1.

    How far does the motorcycle travel from the moment it starts to accelerate (at time t1) until it catches up with the car (at time t2)? Should you need to use an answer from a previous part, make sure you use the unrounded value.


    I plugged distance initial velocity acceleration and time. When I got the distance I divide it by the speed it was traveling and got the time to be 5.57 seconds.
  2. jcsd
  3. Jun 3, 2012 #2
    What part does the 5 second 'wait' period play in the problem?
  4. Jun 3, 2012 #3
    You want the overall time subtracted from the first time so you can get the time it accelerated to the car.
  5. Jun 3, 2012 #4
    You're interested in the time takes to catch up to the car, right?
    So that first 5 seconds can be discarded, because in those 5 seconds no other conditions are changing.
  6. Jun 3, 2012 #5
    Oh ok gotcha now. I got 4.90 seconds for the time it takes the motorcycle to catch the car.
  7. Jun 3, 2012 #6
    That's right! :smile:
  8. Jun 3, 2012 #7
    Finally :) so for the other part of the problem I want to get the speed and use the time from the previous answer to figure out the distance traveled? I get speed/velocity by using V=Vo+aT
  9. Jun 3, 2012 #8
    You can do that, but I find that to be a useless calculation.

    What equation relates time, vo, acceleration, and distance?
  10. Jun 3, 2012 #9
    d=Xo+VoT+1/2aT^2 ?
  11. Jun 3, 2012 #10
    Yessir. Using that should give you the right answer.
  12. Jun 3, 2012 #11
    Alright thanks for the help!!
  13. Jun 3, 2012 #12
    Just curious, what'd you get?
  14. Jun 3, 2012 #13
    168 meters
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