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?
answer/question/discussion: ->->->->->->->->->->->-> :
I chose the pendulum. The first position was approximately 4 inches at 59.359 seconds.
The second was approximately 12 inches at 59.796 seconds. The third was at approximately 15 inches at 60.015 seconds.
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: ->->->->->->->->->->->-> :
The positions could be accurately determined within 0.5 inch. This is because the marks of the inches can be read, but the marks in between cant be distinguished. The clock can be accurately determined by 0.1 second. This was determined by pressing pause and play as quickly as possible. There was a minimum difference of 0.1 seconds. For example, if the clock was at 59.43, it would never stop at 59.48. It would only stop at 59.53 or higher.
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: ->->->->->->->->->->->-> :
Assuming that the pendulum is moving at a constant speed and we start the pendulum movement at the same time as the tape, we know that the tape is speeding up if it moves in front of the pendulum. If it is slowing down, the pendulum would move in front of it. If you pause the video every two inches the tape moves, the difference in time would be smaller each time if the tape was speeding up.
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: ->->->->->->->->->->->-> :
If the pendulum position is paused after every movement of two inches, then we know the pendulum is speeding up if the difference in time is decreasing. If we knew the tape was moving at a constant speed, we know that the pendulum is speeding up if it moves in front of the tape (assuming the movement of the tape and pendulum started at the exact same time).
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I spent about 40 minutes on this question.
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&#Your work looks good. Let me know if you have any questions. &#