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Homework Help: Average speed, and total distance traveled

  1. Sep 8, 2009 #1
    1. The problem statement, all variables and given/known data
    Sally travels by care from on city to another. She drives for 30.0 min at 80.0 km/h, 12.0 min at 105 km/h, and 45.0 min at 40. km/h, and she spends 15.0 min eating lunch and buying gas.
    a.) Determine the average speed for the trip.
    b.) Determine the total disance traveled.

    2. Relevant equations

    Vavg= total distance/time
    Vavg=change in displacement/time

    3. The attempt at a solution
    a.) is 53.5, and b.) is 91 but im not sure how to get them.
    My friend was trying to explain it to me, and said to turn all the minutes into hours and multiple them by the speeds. I did that and got 91, but im not sure why i had to do that.
  2. jcsd
  3. Sep 8, 2009 #2
    what are the units of 53.5? Give units in your answers.
  4. Sep 8, 2009 #3
    a.) is km/h and b.) is km, i figured it out though.
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