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 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?
Pendulum Video 1
Time 59.46 59.68 59.90
Positions 5.5 12 16
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.). You should include an explanations of the basis for your estimate: Why did you make the estimate you did?
I could see the clock clearly; therefore my time measurements had a low uncertainty .01sec
the uncertainty for my positions was a little greater between .5in to .8in. I recorded my positions starting at the front of the pendulum. The numbers were very hard to see so I estimated based on the 1foot mark in the middle.
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?
You can calculate the speed based on change in distance vs. time if the distance is greater in less time then its obvious the tape is speeding down the incline.
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?
Similar to the method used above measure the change in distance vs. the change in time and if the pendulum covers more distance in less time it is speeding up however if the pendulum covers less distance than it is obviously slowing down in addition the length of the swing will be less if it is slowing down
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?
It slow towards the ends of the swing where v approaches 0 and it is furthest from the center. The distance from the center also decreases when it slows down
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?
answer/question/discussion:
I observed the tape speeding up compared to the speed of the pendulum it bypassed the penfulum towards the end of the incline
** **
20min
** **
I dont feel like i got enough information from the video
No experiment can provide 'enough' information. There is always a degree of uncertainty in any measurement.
At some level the scale in the video is difficult to read. The numbers next to the one-inch markings are not clearly legible, but it's possible to count them from the 1-foot markings. However in most frames the blurriness of the object makes it difficult to observe within an inch. It may or may not be possible to observe positions with an uncertainty of +- 1 inch; it may or may not be possible to do so with an uncertainty of +- 1/2 inch; but it almost certainly isn't possible to do much better than that.
The clock times have their limitations also. If a certain clock displays times to within, say, .001 second but the clock only changes every second, then a given event could occur anywhere within that 1 second interval and the clock wouldn't be able to display the difference. The clock in this experiment changes more than once a second, but the same principle applies.