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Phy 232
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: ->->->->->->->->->->->-> scussion (start in the next line):
The object I chose was the pendulum.
The first position was about 3.25 inches at 59.250 seconds.
The second position was about 7.75 inches at 59.678 seconds.
The third position was about 17.5 inches at 59.906 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: ->->->->->->->->->->->-> scussion (start in the next line):
For the positions, I tried to measure as precise as a quarter of an inch, but this was hard to do. They were probably not as precise as they should have been. I would say the position is accurate up to an inch because I could see inbetween which numbers the pendulum was on the ruler.
For the clock time, I measured the time up to three places after the decimal. So in this case, I measured the precision up to 0.001 seconds. This is because that is how precise the clock was, and I pasued it right at the moment that the time was on the screen.
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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: ->->->->->->->->->->->-> scussion (start in the next line):
You can observe if the tape rolling along the incline is speeding up or slowing down by the position and clock times. If at each increment of equal time the position increase is slightly more than the increment before, it is speeding up. If at each increment of equal time the position increase is slightly less than the increment before, it is slowing down. In this case, it looked as though it was speeding 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: ->->->->->->->->->->->-> scussion (start in the next line):
In order to determine whether the swinging pendulum is speeding up or slowing down, you can measure the time it takes to complete a full swing back to its original position. Therefore, you would measure the intial position, how far the pendulum goes to the other side, and the time increments. If in each time increment the pendulum does not go as far as the last time, it is slowing down. If in each time increment the pendulum goes further than before, it is speeding up. If you were simply measuring if it was speeding up or slowing down during the swing, you could measure it the same way as the rolling tape.
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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: ->->->->->->->->->->->-> scussion (start in the next line):
You can measure what location the pendulum starts to slow down by comparing the position and clock times. When it gets close to the location the pendulum starts to slow down, the position should increase at a decreasing rate while the increments are steady. This makes sense because if the position is not increasing as much but is using the same time intervals, the average rate of change will be less than before and it is obvious it is 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: ->->->->->->->->->->->-> scussion (start in the next line):
You could use observations to determine whether the rate at which the tape is speeding up is increasing decreasing or constant by comparing the position versus clock times. If the clock time is in even intervals, it is easy to determine if the rate of increase is increasing decreasing or constant by just looking at the positions. If the position are increasing in increments, the rate is increasing. If the positions are decreasing in increments, the rate is decreasing. If the positions are increasing by the same increment, the rate is constant.
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&#Good responses. Let me know if you have questions. &#