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Two Cars (FUN PROBLEM)

  1. Sep 2, 2009 #1
    Two cars travel westward along a straight
    highway, one at a constant velocity of
    85 km/h, and the other at a constant velocity
    of 107 km/h.


    a) Assuming that both cars start at the
    same point, how much sooner does the faster
    car arrive at a destination 18 km away? An-
    swer in units of h.
    006 (part 2 of 2) 5.0 points


    b) How far must the cars travel for the faster
    car to arrive 18 min before the slower car?
    Answer in units of km.


    So i think the answer for problem A) would be .02 h
    but Im not Sure exactly if im doing this right.
     
  2. jcsd
  3. Sep 2, 2009 #2
    1.78km per min
    18/1.78=10.11235955
    1.41km per min
    18/1.41=12.76595745
    12.76595745-10.11235955=2.6535979
     
  4. Sep 2, 2009 #3
    I try to use my relative speed which is 22kph and my distance is 18km, using t = d/r i come up with .818182 but I dont understand how this applys.
     
  5. Sep 2, 2009 #4
    For your first problem, simply consider how long it takes each individual car to travel 18 km. The second will require a substitution.
     
  6. Sep 2, 2009 #5
    i came up with .04354h and it was right. lol.
     
  7. Sep 2, 2009 #6
    Now i need b)
     
  8. Sep 3, 2009 #7

    rl.bhat

    User Avatar
    Homework Helper

    Let x be the distance.
    Find the time taken by two cars to cover that distance. The difference between the times should be 18 minutes.
     
  9. Sep 3, 2009 #8
    lol..we must go to the same school..
     
  10. Sep 3, 2009 #9
    Lol indep, khs possibly?
     
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