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.
** **
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 depict the same 'roll' down the ramp, at three different clock times. 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 (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?
I chose the first video to clock the tape as it rolls. At a little between the beginning and the first black mark, the tape is clocked at around 58.5 to 59 sec. The next frame I froze was at the black mark and it was clocked at around 60 sec. The final frame was at the end when it hit the ruler and that was clocked at 60.9 seconds.
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.).. I believe I could use the longer video, which would be video 1 to give the best answers which would include positions and clock times of the pendulum as well as the roll of tape. I most likely be able to determine this within the tenth of a second using the clock that is on the screen. After obtaining that information I could use that to help me get more accurate reading on the distance the object moves to a few inches every few seconds.
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? I do believe that it would not be very hard to obtain this observation if you did the exercise where you stopped and played the video. Start by clocking the tape at the beginning when it is first released, then every three to five inches. Do this on more than 2 videos and you should easily be able to tell if it is slowing down or speeding up.
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? You should be able to do this the same way as I explained in the question before. Take observations from more than 1 video and stop it every other frame and measure it from 3 inches, then 6 inches and so on. From this information you should easily be able to obtain the data that is asked.
answer/question/discussion:
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 don’t know if this is the right answer, but you may be able to do this by freezing the frame when the pendulum gets to the end of the ruler the first time and recording the data, then again when it comes back the second time and so on until you feel you have enough data to obtain the answer you are seeking.
answer/question/discussion:
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? You should be able to do this if you clocked it at 2inches for example, then 4 inches, 6 inches and so on until the tape hit’s the ruler and comes to a stop.
answer/question/discussion:
** **
In watching the video and answering the questions I spent around 45 min. to an 1hr.
** **
Very good. In subsequent submissions, be sure to insert your answers after they answer/question/discussion: prompt, so that your answers can be clearly distinguish from the questions.