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Homework Help: Rate of Flow of Fluids Experiment?

  1. Aug 10, 2004 #1
    I'm currently in the process of an extended experimental investigation for senior physics, and having some problems utilising my results and relating them to any kind of theory.
    Here's my sob story:
    My partner and I were initially going to experiment with capillary tubes (eg. Poiseuille's Formula) - a nice simple experiment we thought that we produce some decent results. However, our school decided that the range of tubes we required was too difficult to provide, so they bought us two large pipes about a metre high each with different diameters (9.8cm and 8.3cm), and with 12mm holes drilled in the side at 15cm intervals. The smaller diameter tube also contains holes with different diameters, ranging from 12mm to about 1mm. They instructed us that a similar experiment could be done using these tubes, obtaining the flow rate by measuring the time taken for the trajectory pouring out of one of the holes to travel a certain displacement. Of course, in order for the trajectory to move, the water level and thus the pressure must be decreasing, and any theory i have looked at requires the water height to be constant.
    However, we followed our teacher's advice... We altered the variables of initial height of water (height of hole), diameter of tube, diameter of hole, and how the results were affected when a lid was screwed over the top of the tube. We measured the length the initial trajectory achieved and the time it took to travel a certain displacement. I cannot find any way that this relates to rate of flow? Is there any kind of theory I can investigate or, as i suspect, was this experiment completely pointless?

    P.S. In addition, the results that we obtained when we screwed the lid on seem to be completely arbitrary. Can this be attributable to an air leak in the lid perhaps, or is something else at play here?

    Thanking you all in anticipation
  2. jcsd
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