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Average speed of person walking problem

  1. May 14, 2013 #1
    1. The problem statement, all variables and given/known data

    A person walks first at a constant speed 5m/s along a straight line from point A to point B, and then back along the line from B to A at a constant speed 3m/s. (a) What is her average speed over the entire trip? (b) Her average velocity over the entire trip?

    2. Relevant equations

    Average speed = total distance traveled / total time

    3. The attempt at a solution

    (b) is obviously 0 since start and end positions are the same. For (a), the book gives the answer 3.75m/s. No idea how this came about. Since no time was given, how do you get this answer???
  2. jcsd
  3. May 14, 2013 #2


    Staff: Mentor

    The average speed is (total distance)/(total time).

    If you let d = the distance from A to B, what expression represents the time for her to go from A to B?
    What expression represents the time for her to make the return trip?
  4. May 14, 2013 #3
    d/5 = time from A to B
    d/3 = time from B to A

    k i figured it out thx for ur help
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