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Homework Help: Constant Velocity Confusion

  1. Sep 30, 2008 #1
    I am doing make-up questions from my General Physics test. This is pretty easy stuff, and I thought I answered correctly, but according to my teacher's comments on my paper it seems like I'm missing something.

    1. The problem statement, all variables and given/known data

    For the data provided, is the velocity for this object constant? How do you know?

    Displacement (cm): 15, 100, 190, 290, 380
    Time (seconds): 0, 3, 6, 9, 12

    2. Relevant equations

    3. The attempt at a solution

    Just by looking at the data I would say it's not constant, but after graphing it, the trend curve is linear, so I wrote my answer as

    The teacher seemed to accept the answer as correct, but wanted more information because after my answer she wrote

    Is there any other way to explain the fact that the data is linear?
  2. jcsd
  3. Sep 30, 2008 #2
    I sure would be curious to find out what exactly your teacher wants.
  4. Sep 30, 2008 #3
    Yes, because the trend curve is linear and... you're a great teacher?
  5. Sep 30, 2008 #4


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    Hint: If the line had a significant slope, the v-t graph would still be linear, but the velocity would not be constant (the object would be accelerating).
  6. Sep 30, 2008 #5
    But the graph is for position vs time, which is linear. Therefor the Velocity vs. Time graph would have a slope of 0, making it constant velocity.
  7. Sep 30, 2008 #6


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    You're right, i messed that up big time. So I guess you could say "linear with a slope of v'?
  8. Sep 30, 2008 #7
    PhanthomJay: Yeah, I guess the only information I could add is the trend line equation or the slope value. I guess I'll add that and hope it's good enough, thanks.
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