Purpose
The purpose of our investigation is to analyze the rate at which water flows through holes of varying sizes.
Background
Water is an important substance on Earth; without water there would be no life. Human beings need water to function and because people are always losing water, it is hazardous not to drink enough. If humans don't consume enough water it can result in immobility and even death, among other conditions. There is a fairly large amount of water on Earth. Ninety-seven percent of that water is ocean and dangers for people to consume. Even so, there is more than enough water in rivers and lakes, both above and below ground, which is why we're able to use lots of water, from a garden hose for our experiment.
Water
falls to the ground in drops because water molecules clump together. If there
were no gravity on earth, the drop would form a sphere instead of a drop shape.
Galileo performed an experiment where he proved that objects fall to the ground
with the same velocity. He used a water clock to measure the time it took for an
object to reach the ground. We will, instead, measure how much time it takes for
the water to flow out. Area and flow rate formulas can be referenced to in our
experiment. The volume rate would be VA, where V would be the volume in meters
cubed, A would be the area in meters squared, and the answer would be m^3/s. or
meters cubed per second. The formula for the flow rate would be V=2gh^(1/2),
where V equals the volume in meters cubed, g would be the constant for taking
account of gravity, -9.8, and h would equal the weight in meters.
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Hypothesis
We
believe that the rate at which water flows depends on the size of the hole.
Therefore, if the diameter of the hole becomes larger, then the rated at which
the water flows through that hole will increase. We will experiment with
thirteen different-sized holes whose diameters will be decreasing at a constant
rate. If our hypothesis is right, we will see in our data an increase in flow
rate as the diameter of the holes get larger.
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Method
Our
experiment set up includes a very large bucket, with which we’ve drilled
thirteen different-sized holes with different drill bits. The diameter of every
hole decreases with each hole at a gradual constant rate. We used sand paper to
smooth out the edges of the holes so the flow rate wouldn’t be affected. The
set up also includes a clear glass container, which holds one liter of water. A
garden hose is used in order to keep the height of the water in the bucket at a
constant rate so the pressure in the bucket remains constant. We used a
stopwatch that records down to the hundredth of one second.
First,
we taped up all holes except our first hole with duct tape and filled up the
bucket to the top with water, making sure the hose was still on so the pressure
in the bucket stayed constant. Once the bucket was full we placed the container
under the stream of water and timed how long it took to fill up to the one-liter
mark. We recorded three trials for each hole, making sure we taped and untapped
the proper holes and making sure we didn’t have any leaks. The total
experiment ended up taking quite a long time as the last holes took several
minutes to fill up the container for each trial.
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Data
The
data we recorded was put into Microsoft Excel and with Excel we created graphs
of the average times for each hole to fill one liter and of the average flow
rate for each hole. We calculated the flow rate of each hole by dividing one
(liter) by the time it took the water to flow out. The curves of the graphs show
an exponential-like increase in the time it takes for the liter container to
fill up and a decrease in flow rate as the holes get smaller and smaller in
diameter.
Data: Text
.:. Excel
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Conclusion
Our
hypothesis was correct; our data shows that as the size of the diameter of the
holes increases, the flow rate also increases. So even though the holes got
smaller and smaller at a gradual, constant rate, the flow rate decreased at a
rate that changes as the hole gets smaller. This could be due to the water that
is fairly slow right around the edges of the holes and much quicker in the
center of the flow. As the holes get smaller, there is less area and more of the
water is slowed down by the edges of the holes. But the larger holes have more
area, where more water isn’t slowed down by the edges of the holes.
There are, of course, inaccuracies in our experiment. We didn’t account
for any runaway drops of water that didn’t make it into the container, which
very slightly affects the data collection. Also, we didn’t have some sort of
automated timer; we, as humans, aren’t exact timers due to our reflexes,
sight, etcetera, so the times could possibly be exactly accurate but they were
close enough that we could see a pattern in our data. Lastly, we weren’t able
to sand the inside of the smaller holes because they were so small in diameter,
but this shouldn’t have affected the outcome very much. Otherwise, our
experiment was pretty accurate.
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Links
To Related Works
1) <http://ga.water.usgs.gov/edu/waterproperties.html>
Helped us with information about the properties of water.
2) <http://www.spartechsoftware.com/reeko/Experimetns/ExpRacingJars.htm>
This website showed us an experiment similar to another experiment pertaining to
our project.
3) <http://www.angelfire.com/ct/christaylor/water.html>
Another website that helped explain water experiments.
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