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:
• Write down the position and clock time of one of the objects, as best you can determine them, in each of three different frames. This means that for each of the three readings, you just 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, 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:
The pendulum was the object that I chose. The 3 positions were approximately 0, 8, and 18 inches and the clock times were 39.812, 40.687, and 41.453 sec respectively.
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 such observations:
• If you did take observations of positions and clock times, how accurately do you think you could determine the positions, and how accurately do you think you would know the clock times?
answer/question/discussion:
I believe that the positions were accurate within 1 inch because the scale was difficult to see. If it was easier to see the scale then the position readings would probably be within +/- 1/8 inch. The clock times would be accurate within +/-0.2 sec because of the inaccuracy that comes with human reaction time in starting the measurment.
• How can you use observations to determine whether the tape rolling along an incline is speeding up or slowing down?
answer/question/discussion:
You can use the observations to determine the position in relation to clock time. By dividing each of the three positions by their respective clock time you could determine whether the tape is speeding up or slowing down. The lesser the inches /sec the tape is speeding up, the greater the inches/sec the tape is slowing down.
• How can you use your observations to determine whether the swinging pendulum is speeding up or slowing down?
answer/question/discussion:
You can determine whether the swinging pendulum is speeding up or slowing down in the same manner as used for the roll of tape.
• 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:
In the same manner as above for the pendulum. When the inches/sec begins to become larger, it is slowing down.
• 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:
Plot the positon vs. clock time on a graph. If the slope of the line is steeper when traveling up to the right, then the speeding up is increasing. If the slope is not changing then the speeding up is constant. If the slope is decreasing steeply toward the bottom right, then the speeding up is decreasing.
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30 minutes
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Excellent answers.