Rate of Flow of Fluids Experiment?

[jengshe]

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

 

[member 553083]

for your help. Unfortunately, the experiment that you were given does not seem to fit any known theory that would allow you to calculate the flow rate. It is possible that there is some other unknown or unpublished theory that could be used to analyse your data, but without more information it is difficult to say. The results that you obtained when you screwed the lid on could be due to an air leak in the lid, but without knowing the exact setup it is difficult to say for sure. It is also possible that the lid itself created some turbulence in the water which affected the flow rate, or that the lid was not perfectly sealed which caused some air to enter the tube and affect the flow rate.

 

[M98Ranger]

First of all, I commend you for taking on an extended experimental investigation for your senior physics project. It can be a challenging and rewarding experience, and it's great that you are seeking help and advice to improve your results.

It sounds like you and your partner had a clear plan for your experiment, but unfortunately, it was changed due to limitations with the equipment provided by your school. This can be frustrating, but it's important to be adaptable and make the best of the situation. It seems like your teacher tried to provide an alternative experiment that would still yield meaningful results, but it's understandable that you are having trouble relating your findings to any theory.

In terms of the theory behind rate of flow, there are several equations and principles that can be applied to your experiment. For example, Bernoulli's equation can help explain the relationship between pressure and velocity in a fluid. The continuity equation can also be used to relate the cross-sectional area of a pipe to the velocity of the fluid flowing through it. These are just a few examples of theories that can be relevant to your experiment.

As for the results when you screwed the lid on, it's possible that there was an air leak or some other factor that affected the flow of water. It's important to carefully control all variables in an experiment, but sometimes unexpected factors can still influence the results. It's important to document any potential sources of error and try to replicate the experiment to see if similar results are obtained.

In conclusion, while it may have been frustrating to have your original experiment plan changed, it's important to remain open-minded and try to make the best of the situation. There are theories and equations that can be applied to your experiment, and it's worth exploring them to see if they can help make sense of your results. And don't forget to document any potential sources of error and try to replicate the experiment to ensure the validity of your findings. Best of luck with your project!