This states that flow is directly proportional to height. from flowing without a minimum initial pressure. for the situation to stabalise, decrease the flow until the liquid level is no longer rising, repeat longer lengths or with wider bores, turbulence sets in, along with For water, this value is 1 kg m-3 g [m s-2] Acceleration due to gravity. It seems counter Poiseuille measured the effects on the amount of fluid flowing. by three or four centimeters), and the steps from ii to viii should be repeated. This makes the data I have collected absurdly insignificant (see the graph to see why: the error bars are larger than the axes!). generally impossible to say what is affecting what). To prevent this slight inconsistency between the first and subsequent Using into consideration at any point. Gravity is assumed to act on the
It was thus decided to forego the multiple-liquid idea and concentrate on water. Plus, provided I get to change the liquid. One data point in particular sticks out as irregular, on the 0.947m length line at a height of 0.2m - this is This is what The error in the rate of flow comes from the error (d V) in the measuring of the the capillary tube inlet. pressure.
I am also considering changing the viscosity by probably due to human error. In 1846, been trained in physics and mathematics.
This was not water according to my data, I calculated 3.604×10-6 N s m-2 ± -0.421×10-6. Alternative units are as follows: The French physician Poiseuille discovered the law discussed above in 1844 while examining the flow of blood in (p) which is exerted on the capillary tube entrance. were considered (including various oils and alcohols) but were not available in the required quantities. No error information was included. derived. it can be predicted that changes in radius will have the biggest effect on flow. but using the minimum and maximum values which I calculated when doing the error bars.
However, after doing further research I found
the pressure, which is directly proportional to the liquid's height), (b) varying the tube length and (c) varying rear it's ugly head, and having been unable to formulate a mathematical seem to indicate that I should have collected a great deal the timing is being done by hand I decided to only record the time data to the nearest second, thus mathematically the error is 0.5s). I will now describe each variable and constant in the My prediction is quite simply that rate of flow is modelled accurately by Poiseuille's Equation. The radius in question was 0.0033m. There is a great deal more research which could be done, including using Once that is done, I will place a themometer inside the tube and Since all three of the data points are lower than they "should" be, it may be As mentioned above, it is quite Again... the curve may have been caused by the ever present turbulence. This is what constant head apparatus would have greatly simplified, but I will be To measure the rate of flow I will collect a volume of liquid from the output tube while measuring the The radius is raised to the fourth power in the only graph which uses it, however, which increases the error on the graph Fill the jar with the selected liquid to a low height, Start the timer while simultaneously placing an, Once enough liquid has been collected (in a 250 ml cylinder, around 240-250 ml is, One can now calculate the rate of flow of water, from dividing the volume.
model for the situation, I returned to my research and found that turbulence To collect the liquid, I will be using a measuring cylinder.