Phy 201
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 do not 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?
I chose object # 1 and my three positions and clock times were as follows:
1 inch @ 59.031 sec
5 inches @ 59.468 sec
17 inches @ 59.796 sec
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 do not believe that you could determine the position nor clock time with a great deal of accuracy due simply to the poor visibility. The clock times may be slightly more accurate due to being stopped precisely on a time, however sometimes the video was stopped while the clock was changing causing a blur of numbers. The positions could be measured pretty accurately to the nearest half inch, but anything smaller than that would be very hard and would most likely affect the accuracy in a negative way.
• 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?
Based on my observations after the first 4 tenths of a second the tape had moved 4 inches, but in the last 3 tenths the tape moved 12 inches so it is easy to see that the tape is speeding up.
• How can you use observations of position and clock time to determine whether the swinging pendulum is speeding up or slowing down?
You can determine whether or not the pendulum is speeding up or slowing down by doing the same thing I suggested for the tape. Observe the change after the first 4 tenths and then after the last 3 tenths
• 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?
Well, I would assume that a pendulum speeds up on the down stroke and immediately begins to slow down upon entering it’s upstroke. If this were the case, one could observe the position at which the pendulum begins it’s upstroke and measure the rate of change on the down stroke to that of the upstroke and if the rate of change of the upstroke is less than that of the down stroke then the location at which the pendulum starts slowing down would be precisely as it enters it’s upstroke.
• 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 could take a measurement every 4 tenths of a second and see how many inches the tape has moved. If that rate of distance per time remains the same, then it is constant. If the tape moves farther each measurement than it is increasing. If the tape moves less each time than it is decreasing.
** **
Approximately 25 min
** **
&#Very good responses. Let me know if you have questions. &#