Our experiment was designed to find how much air would be needed to lift certain weights from certain depths. Our results showed that you need more air to lift heavier weights, but there was something else that puzzled us. We had thought that you would need less air to lift weights at deeper depths (see our hypothesis) but it turned out that the amount of air was relatively the same. Our hypothesis had been on the basis that water buoys up objects more at deeper depths. It seemed to make sense at the time but once we thought about our actual results we realized why this had occurred. The volume of air that you need to buoy up an object of certain weight is always the same. Since air is compressed the farther down you go the more condensed the air is also. This meant that although there was more air is terms of density there was the same amount in terms of volume. This stayed the same as even as the depth changed because at deeper depths there is more pressure and at lesser depths there is less pressure. Each time the balance between pressure, volume and density was balanced.
I think that our experiment was very well designed, and, we found out, it worked exactly as it was supposed to. One of our main difficulties at the beginning of the experiment our platform was upside down, with the attached weights and bottles on the underside. Also, when we righted the platform, one of the lifting bottles had become untied. Fixing these problems caused certain parts of the experiment to be less accurate. Another problem we encountered was that the Purge Valves we were using to fill the bottles were not very accurate. Often we would put too much air in the bottles, and because the weights were tied down we could not tell if that was the right amount of air or if was way too much. The last major concern was that writing on the bottles underwater was not easy and the water currents would make our hands and the bottles unsteady.
The results on our table might seem fairly far away from the
other results from the particular weight. In fact they are not
very far away at all. We tried to find the amount that the highest
and lowest results were off to see how much error we had
Here is a table of our largest differences in results:
Depth (ft): 4 Bolts: 7 Bolts: 10 Bolts:
Difference: 100 ml 130 ml 200 ml
With the margin of error that we experienced the results were close enough to be called the same for each weight.
Our results were quite close to what they should have been, even though we had not expected them. By doing this experiment we learned a number of things. The first is that the volume of air needed to lift a weight does not change (much) with depth. The second thing I learned is that being prepared is very, very important for a successful project.
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