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Phy 241
Your 'cq_1_00.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
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The problem:
You don't have to actually do so, but it should be clear that if you wished to do so, you could take several observations of positions and clock times. The main point
here is to think about how you would use that information if you did go to the trouble of collecting it. However, most students do not answer these questions in terms
of position and clock time information. Some students do not pause the video as instructed. To be sure you are thinking in terms of positions and clock times, please
take a minute to do the following, which should not take you more than a couple of minutes:
Pick one of the videos, and write down the position and clock time of one of the objects, as best you can determine them, in each of three different frames. The three
frames should all depict the same 'roll' down the ramp, i.e. the same video clip, at three different clock times. They should not include information from two or more
different video clips.
For each of the three readings, simply write down the clock time as it appears on the computer screen, and the position of the object along the meter stick. You can
choose either object (i.e., either the pendulum or the roll of tape), but use the same object for all three measurements. Do not go to a lot of trouble to estimate the
position with great accuracy. Just make the best estimates you can in a couple of minutes.
Which object did you choose and what were the three positions and the three clock times?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
I chose VIDEO 3 and the roll of tape.
I estimated the ramp to be about 24 inches (2 feet) total.
Starting point of experiment: approx. at 27.1 seconds
Released at: approx. 28.8 seconds
When tape was halfway down the ramp (12 inches): approx. at 29.3 seconds
When tape was 3/4 of the way down the ramp (18 inches): approx. at 29.562 seconds
When tape hits bottom of ramp (24 inches): approx. at 29.6 seconds
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In the following you don't have to actually do calculations with your actual data. Simply explain how you would use data of this nature if you had a series of several
position vs. clock time observations:
If you did use observations of positions and clock times from this video, how accurately do you think you could determine the positions, and how accurately do you
think you would know the clock times? Give a reasonable numerical answer to this question (e.g., positions within 1 meter, within 2 centimeters, within 3 inches, etc;
clock times within 3 seconds, or within .002 seconds, or within .4 seconds, etc.). You should include an explanations of the basis for your estimate: Why did you
make the estimate you did?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
Using the pause button several times, I stopped the video at the different positions I chose and recorded what the clock time was. I measured in inches and did
fourths of a foot intervals. (6 in, 12 in, 18 in, 24 in) I feel like my data is accurate, according to the clock time shown in the video and where I stopped it at. Obviously,
the roll of tape isn't going to be exactly at the place I said it was at the exact clock time. I could probably determine the positions within 3 inches, since I estimated the
entire ramp to be 2 feet. I could probably determine the clock times within about 0.5 seconds, since the clock timer is moving very fast and when I stop the video, it
becomes blurry and several numbers after the decimal point are run together, therefore, I couldn't get it to the exact, but close.
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How can you use observations of position and clock time to determine whether the tape rolling along an incline is speeding up or slowing down?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
According to the data I took, it's clear that the roll of tape speeds up along the incline. For example:
(at approx. positions):
1 inch was at 27.1
6 inches was at 29.1
12 inches was at 29.3
18 inches was at 29.562
24 inches was at 29.671
You can see that the intervals become closer and closer in clock time near the end of the ramp, therefore it speeds up.
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How can you use observations of position and clock time to determine whether the swinging pendulum is speeding up or slowing down?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
I also took data on the pendulum, and it was clear that from starting point to 12 inches, the pendulum was faster than the roll of tape, in that interval. However, from 12
inches to the end of the ramp (24 inches), the roll of tape was ahead or faster than the pendulum.
(at approx. positions):
1 inch was at 27.1
12 inches was at 29.343
15 inches was at 29.562
24 inches was at 30
You can see the difference between the data of the roll of tape and the pendulum, that from halfway to the end of the ramp, the roll of tape's clock times were smaller,
therefore faster than the pendulum. HOWEVER...I also, watched the pendulum's HALF oscillations from where it started and saw these results:
(APPROX.)
27.1 seconds to 30 seconds (2.9 seconds difference)
30 seconds to 31.312 seconds (1.312 seconds difference)
31.312 seconds to 32.3 seconds (0.988 seconds difference)
This shows that the swinging pendulum IS speeding up.
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Challenge (University Physics students should attempt answer Challenge questions; Principles of Physics and General College Physics may do so but it is optional for
these students): It is obvious that a pendulum swinging back and forth speeds up at times, and slows down at times. How could you determine, by measuring
positions and clock times, at what location a swinging pendulum starts slowing down?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
From MY data, it shows that the swinging pendulum is the slowest from start to the end of the ramp then gradually speeds up from then on. To determine at what
location a pendulum starts slowing down, I would take tons of data. I would measure at several positions what the clock time is, and do like I did above, record the
HALF oscillations and see what the difference in seconds is from one oscillation to another. The differences will show at what point it starts slowing down.
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Challenge (University Physics students should attempt answer Challenge questions; Principles of Physics and General College Physics may do so but it is optional for
these students): How could you use your observations to determine whether the rate at which the tape is speeding up is constant, increasing or decreasing?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
I would take a lot of data, several positions and the clock times, and GRAPH my data. This will show me what the points are doing and will determine if it's constant,
increasing or decreasing. I graphed my data, of the roll of tape, and saw that the graph starts out increasing then gradually starts decreasing the furthur it goes. So, I
would say the rate at which the tape is speeding up is decreasing.
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30 minutes
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&#Your work looks very good. Let me know if you have any questions. &#