Phy 231
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 pendulum and I recorded the times of 29.015, 29.453, and 29.671 with the positions of 3in., 12in., and 19in. respectively.
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 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:
It would depend upon the equipment that I used for the experiment in how accurately I could measure time and position. With this equipment I would not expect to be able to measure position more accurately than in inches and I would not expect to be able to measure time better than tenths of a second; however, for greater accuracy I would use a laser to measure the position while simultaneously using a synchronized timer running on a computer with the appropriate program compiling the data and matching the respective times and positions.
• 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:
I would average the positions at a specific time as the tape rolls and calculate the rate of speed at each of the average values. I would then find the differences between the points, and if the differences were increasing then the rate was increasing and if the differences between points were decreasing across equal intervals of time then the rate would be decreasing.
• 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:
Essentially I would calculate the differences of positions across different positions same as I would for the tape as I explain in the above answer.
• 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:
The differences between positions would be smallest for given equal intervals of time when the pendulum is swinging at its slowest; therefore, the point at which the different positions before and after it are smaller than all other such differences would be were the pendulum is slowest.
• 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:
When calculating the differences in positions at different times we are finding the rate of change of position or velocity. If then find the differences in velocities at individual points we will then being find the acceleration or rate of change of the rate of change for the pendulum. If the acceleration is positive then the velocity is increasing, negative then the velocity is decreasing, and if the there is zero acceleration then the speed is constant.
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32 minutes
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&#Very good work. Let me know if you have questions. &#