phy 121
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?
Video 1
1” at 59.1
17” at 59.8
22” at 60.2
answer/question/discussion:
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?
Because of being able to pause the video I believe that I could make fairly accurate calculations. I would say within ½ in. on measurement and .5 sec. on time or better.
Good. In the future put your answers after the answer/question/discussion: prompt; no problem this time but it will be easier for both of us to locate your answers in posted documents if you follow this format.
answer/question/discussion:
• 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?
To see the distance covered in the amount of time as it goes down the ramp.
answer/question/discussion:
• How can you use observations of position and clock time to determine whether the swinging pendulum is speeding up or slowing down?
To see the distance covered in the amount of time as it proceeds down the ramp.
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5 - 10 min. or so . I got up a couple of times so I'm not exactly sure.
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Your work looks good. See my notes. Let me know if you have any questions.