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Homework Help: What is the cyclist's end position? I know his displacement.

  1. Sep 13, 2011 #1
    1. The problem statement, all variables and given/known data

    I can't figure out part two to a problem. The first part asked us to find the displacement, but I'll let you read for yourselves:

    Part 1: A cyclist maintains a constant velocity of
    5.3 m/s headed away from point A. At some
    initial time, the cyclist is 259 m from point A.
    What will be his displacement from his
    starting position after 83 s?
    Answer in units of m

    Part 2: What will be his position from point A after
    that time?
    Answer in units of m

    I solved part 1 and my answer was (from point A)[itex]\Delta[/itex]x = 439.9m which I know is correct.

    2. Relevant equations

    I didn't use an equation, I just did it in steps that I made up. Maybe xf = vt + xi would work?

    3. The attempt at a solution

    I solved part 1 by dividing the cyclist's distance from point A (259m) by his velocity (5.3m/s) to get the seconds it took (48.8679) to travel 259m. I then set up a proportion with these values to solve for the displacement that the question was asking for, which was 439.9m.

    I'm not sure how to find out what his position will be at 83s. I thought it might have been identical to the displacement, but there is really no given starting point value... It wouldn't be 439.9 + 259, would it? I feel like they left out the starting position value. Maybe A + 439.9?

    Any help would be greatly appreciated!
    Last edited: Sep 13, 2011
  2. jcsd
  3. Sep 14, 2011 #2


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    Staff Emeritus
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    Gold Member

    It would be that yes.
  4. Sep 14, 2011 #3
    Thanks! I always end up figuring it out (sometimes without realizing it) when I write out my thoughts here. Thanks!
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