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Homework Help: Average Velocity issue

  1. Sep 1, 2010 #1
    1. The problem statement, all variables and given/known data
    A motorist drives for 35 minutes at 85km/h and then stops for 15.0 minutes. He then continues traveling 130km in 2 hours. a) What is his total displacement? b) What is his average velocity?

    2. Relevant equations
    v= ∆X/∆t (Change in displacement over change in time)

    3. The attempt at a solution
    I divided 85/km/h and 60 minutes. That makes 1.42 km/m. I timed that by (35) minutes and for the first leg he traveled 49.7km. During the 15 minute break he traveled 0. During the second leg that distance was given (130km). So, 49.7km + 130km gives us the displacement of 180km (roughly).

    Now I'm having a hard-time with the average velocity. I use to above formula and get 180km/170minutes (180km is the change in displacement and 170 minutes is the change in time (35m+15m+120m). The answer 1.06km/m seems a little weird to me.
  2. jcsd
  3. Sep 1, 2010 #2
    I figured out what I did wrong. I can't find the delete option.
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