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Homework Help: Graphical Analysis of Motion

  1. Feb 13, 2010 #1
    1. The problem statement, all variables and given/known data
    1a) What type of motion does a cart experience by rolling down a ramp?

    2a) Compare values of avg velocity and inst. velocity from your data tables. What conclusion can you draw?
    2b) Would the same conclusion apply for non-uniform acceleration?

    3. Your average velocity versus time graph may not pass through the origin. Why?

    http://i45.tinypic.com/2r2yn0o.jpg

    Here are my graphs; the top one is the position vs time graph and the second one is avg velocity versus time (assume it's a straight line & linear). Assume the acceleration vs time graph is also a straight horizontal line.


    2. Relevant equations



    3. The attempt at a solution

    1a) It experiences uniform motion because the average velocity is constant.


    2a)
    Avg velocity vs time
    v(cm/s) t(s)
    7 0.05
    9 0.15
    13 0.25
    17 0.35
    19 0.45
    22 0.55
    25 0.65
    28 0.75
    30 0.85
    32 0.95
    35 1.05
    37 1.15
    39 1.25
    42 1.35
    44 1.45
    46 1.55
    49 1.65
    51 1.75
    53 1.85
    55 1.95
    58 2.05

    Inst velocity vs time
    v(cm/s) t(s)
    7 0.05
    9 0.15
    13 0.25
    20 0.35
    23 0.45
    26 0.55
    26 0.65
    30 0.75
    31 0.85
    31 0.95
    33 1.05
    35 1.15
    36 1.25
    44 1.35
    44 1.45
    46 1.55
    47 1.65
    51 1.75
    52 1.85
    53 1.95
    57 2.05

    The values are fairly similar although avg velocity appears to be more accurate because inst. velocity pauses at certain points indicating its speed stops increasing and then suddenly starts again.

    2b) I'm not sure about this, it's confusing.


    3. My avg velocity vs time graph doesnt pass through the origin because i used the midpoints for each time interval, and it is impossible to use 0 as a midpoint because time cannot go negative.
     
  2. jcsd
  3. Feb 13, 2010 #2
    Your average velocity cannot be constant, look at your data, it's increasing linearly.
     
  4. Feb 13, 2010 #3
    Constantly increasing I mean. Is that not the same?
     
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