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course Phy 202
1/29 8 pmBrief flow experiment
Poke a small hole in the side of a plastic bottle, near the bottom.
Place three marks on the bottle, on at the top of the cylindrical section of the bottle, one halfway between the first mark and the hole, and one halfway between the second mark and the hole.
Place the open piece of tubing with the greater diameter into the hole, and fill the bottle (hold your thumb over the tubing, and do this near a sink or tub, or outside).
Hold the bottle vertical and release your thumb. Determine, as accurately as you can using a clock or watch with a second hand, the clock times at which the water reaches the first mark, the second, the third and the clock time at which the flow from the hole reduces to the point where it leaves the hole in distinct drops.
Report the vertical positions of the three lines, relative to the hole, and the observed clock times.
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14 cm, 6 sec
7 cm. 16 sec
3.5 cm, 27 sec
Start to drip, 40 sec
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Repeat, this time observing how far the water stream travels in the horizontal direction as it falls to the sink, the ground, the tub, etc., when the water level is at each of the three marks. Try to make observations accurate to within a centimeter or two.
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14 cm--32 cm
7 cm—13 cm
3.5 cm—8 cm
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Submit in the usual manner. Once we're sure you have reasonable data, we'll get into the analysis.
Hang onto the bottle for a couple of followup experiments (each equally short).
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Data look good, but you appear to have used only two lines on the bottle.
Fortunately this can be repeated in just a few minutes. You will need to observe four points, one for each of the three lines described in the instructions and one for the beginning of the drip.
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@& Followup to flow experiment:
Using your data from the flow experiment (or if necessary corrected data), you will sketch two graphs:
The first graph will be of depth vs. clock time, where depth is the depth of water relative to the hole.
The second will be of the horizontal range of the stream vs. the depth of the water.
There will be four points on each graph, corresponding to four events. The four events are water reaching the first mark, the second mark the third mark and the water beginning to drip from the hole.
You should then sketch a smoothly changing curve which you think best describes the trend of your data. There are significant uncertainties in the experiment so it is unlikely a well-drawn smoothly changing curve representing the trend will actually pass through any given data point.
Construct your graphs and briefly describe them.
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On the average how close was your curve to your data points?
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Use your data to make a table of the horizontal range of the stream vs. clock time. Give your table below.
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Sketch a graph of your new table, and describe your graph.
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Does the horizontal range of the stream appear to change at a constant, an increasing or a decreasing rate?
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Using your graphs predict the following:
The clock time at which the depth is 8.3 cm.
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The horizontal range of the water stream at clock time 6.4 seconds.
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The average rate at which water depth is changing 7 seconds after the water surface passes the first mark.
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The average rate at which the horizontal range of the stream changes.
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If you haven't already reported it, report how far below the hole the surface was onto which the water stream fell.
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