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Homework Help: Terminal velocity of a steel ball

  1. Nov 16, 2005 #1
    Hi I doing a coursework on finding the terminal velocity of a steel ball in a liquid at different temperatures

    How is my graph suppose to like? My two variables are temperature and terminal velocity (i got my terminal velocity from speed = distance / time)
    And if possible, if you know it, what will the line look like? Is it porportional?
  2. jcsd
  3. Nov 16, 2005 #2


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    What does the graph from your data look like?
  4. Nov 16, 2005 #3
    I have temperature on the x axis, and terminal velocity on the y axis. My line is linear, and i think its porportional like a 45 degree line, except the last point which must be an anomalie
  5. Nov 16, 2005 #4


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    These weren't experimentally determined were they...
  6. Nov 16, 2005 #5
    sorry mate i dont understand what ure on about 'experimentally determind" of course my results are inaccurate. the actual formula for finding terminal velocity is way more complex than that , but my teacher insisted on it man.
  7. Nov 16, 2005 #6


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    Depending on how you made your measurements, that last point may reflect a situation where the ball hadn't reached terminal velocity - just a guess.
  8. Nov 16, 2005 #7
    Yeah I guess so, whats really weird about the whole thing is that the whole experiment was based on a programme, we just had to time the steel ball reaching the bottom
  9. Nov 20, 2005 #8
    Increase in temperature lowers the viscosity

    Terminal velocity = (2 / 9) (r² g / η) (ρ - ρ')

    Where r=radius, g=gravity, η=viscosity, ρ= density of steel, ρ'=density of the liquid

    So, if η decreases, velocity increases.
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