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:
• 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?
The object that I chose was the white tape. For the first position, I chose the time of 59.796 which shows the tape halfway down the platform and the pendulum still touching/pushing the tape down the ramp. The second position, I chose the time of 41.015 which shows the tape away from the pendulum and gaining momentum by speeding up down the slope. The third position, I chose the time of 29.234 which shows the tape gaining momentum but the pendulum is in front of the tape so I cannot really tell if it is restraining it from the speed or not.
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?
I think that it would be fair to say that the data that is collected can help determine the positions and if the clock times effect the outcome.
• How can you use observations to determine whether the tape rolling along an incline is speeding up or slowing down?
The tape was rolling down so due to gravity it is a fair assumption that the incline was making the tape roll speed up.
• How can you use your observations to determine whether the swinging pendulum is speeding up or slowing down?
I felt that the pendulum was going at a constant rate it wasn’t really speeding up or slowing down. I feel that if the video was a bit longer, there could be more observations to be made for that.
This answer is not based on observations of position and clock time. How could you use observations of position and clock time to determine the answer to this question?
• 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?
I would guess that here if we make an assumption, the pendulum could be seen as slowing down after pushing the tape because previously it was restrained to move.
• 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?
Through observations, I would say that the tape was speeding up at an increasing rate because the end results shows that the tape literally bounces off the ramp because of the speed. If the tape was speeding up and the rate was constant or decreasing there might have been an opposite reaction.
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On the questions, I spent around 20 to 25 mins.
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Good, but see my one note and please submit a copy of the note and your best response to the question I posed there.