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Homework Help: Postion problem

  1. Sep 6, 2013 #1
    We are given a velocity vs. time graph. It starts at 15 m/s at t=0 and goes to -10m/s at t=4
    then it goes from -10m/s at t=4 to 15m/s at t=10 and we are told to find the postion after t=10

    I first found the slope of the first segment which was -6.25. so I did ∫-6.25t+15 dt from 0 to 4 and got 10m
    I found the second slope, 4.16...., and did ∫4.16...t-10 dt from 0-6 (because I moved it to the orgin so it made sense) and got 15m. So I added the two segments to get 25m. But the site keeps saying that's the wrong answer. What am I doing wrong?
  2. jcsd
  3. Sep 6, 2013 #2
    Does the sight care about significant figures? Hard to believe ∫4.16t-10 dt comes out to exactly 15m.
  4. Sep 6, 2013 #3
    It comes to 15 when you put 25/6 which is 4.16 repeating. But yes the site does care about significant figures.
  5. Sep 6, 2013 #4
    oh, I didn't do the math myself I just took it as 4.16 flat. Well I did the math myself as well as taking the area under the curve of the graph and got the same answer as you both ways. Honestly at this point I would say they possibly put in a wrong answer for the problem since it's electronic. I know that's happened to people I know before so you might as well ask.
  6. Sep 6, 2013 #5
    ok thank you for your help!
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