course phy 202
ph2 query 0Most queries in this course will ask you questions about class notes, readings, text problems and experiments. Since the first two assignments have been lab-related, the first two queries are related to the those exercises. While the remaining queries in this course are in question-answer format, the first two will be in the form of open-ended questions. Interpret these questions and answer them as best you can.
Different first-semester courses address the issues of experimental precision, experimental error, reporting of results and analysis in different ways and at different levels. One purpose of these initial lab exercises is to familiarize your instructor with your work and you with the instructor 's expectations.
Comment on your experience with the three lab exercises you encountered in this assignment or in recent assignments.
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Question: This question, related to the use of the TIMER program in an experimental situation, is posed in terms of a familiar first-semester system.
Suppose you use a computer timer to time a steel ball 1 inch in diameter rolling down a straight wooden incline about 50 cm long. If the computer timer indicates that on five trials the times of an object down an incline are 2.42sec, 2.56 sec, 2.38 sec, 2.47 sec and 2.31 sec, then to what extent do you think the discrepancies could be explained by each of the following:
The lack of precision of the TIMER program.
To what extent to you think the discrepancies are explained by this factor?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
The timer program is usually accurate to 0.1. the mean of the data set was 2.428. when 0.1 is added and subtracted to the mean, the range of possible error due to the timer program becomes 2.328-2.528. there are still data p oints outside this range, so the timer program error cannot account for all of the error in the data.
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The uncertain precision of human triggering (uncertainty associated with an actual human finger on a computer mouse)
To what extent to you think the discrepancies are explained by this factor?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
Given that outside the known error of the timer program, there is only a 0.03 error on one data point, one could conclude that a persons trigger reflexes are inaccurate to 0.03 seconds.
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Actual differences in the time required for the object to travel the same distance.
To what extent to you think the discrepancies are explained by this factor?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
Although there are some discrepencies in the data, I do not believe that the actual differences in the time for the object to travel the same distances plays a major role
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Differences in positioning the object prior to release.
To what extent to you think the discrepancies are explained by this factor?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
The difference in positioning would also be an attribute of human error, and given that the error itself is only ~0.13 seconds for the whole data set, it is very likely that a fraction of that is due to the human error of positioning.
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Human uncertainty in observing exactly when the object reached the end of the incline.
To what extent to you think the discrepancies are explained by this factor?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
This human error may explain 0.001 or so of the total error, but not an extensive amount of the error itself. In comparison to the other errors present, the perception of the human eye is probably the least inaccurate.
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Question: How much uncertainty do you think each of the following would actually contribute to the uncertainty in timing a number of trials for the ball-down-an-incline lab?
The lack of precision of the TIMER program.
To what extent to you think this factor would contribute to the uncertainty?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
The timer program will probably contribute a maximum of 0.1 points error.
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The uncertain precision of human triggering (uncertainty associated with an actual human finger on a computer mouse)
To what extent to you think this factor would contribute to the uncertainty?
Your answer:
The human trigger will probably contribute no more than 0.03 points of error
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Actual differences in the time required for the object to travel the same distance.
To what extent to you think this factor would contribute to the uncertainty?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
This error would not contribute a significant amount (~0.01 error)
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Differences in positioning the object prior to release.
To what extent to you think this factor would contribute to the uncertainty?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
This human error would be the most problematic, potentially contributing to ~0.1 points in error
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Human uncertainty in observing exactly when the object reached the end of the incline.
To what extent to you think this factor would contribute to the uncertainty?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
The perception of the human eye wouldnt contribute more than 0.001 points of error to the experimetn
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Question: What, if anything, could you do about the uncertainty due to each of the following? Address each specifically.
The lack of precision of the TIMER program.
What do you think you could do about the uncertainty due to this factor?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
Nothing. A 0.1 error in the program is pretty precise, and using a computer program does have limitations, but they are much better than if a person was timing themselves.
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The uncertain precision of human triggering (uncertainty associated with an actual human finger on a computer mouse)
What do you think you could do about the uncertainty due to this factor?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
To minimize this error, a person would have to make sure they are alert to the fullest. This means that a tired person will probably have more flawed results. other than that, this is just inherent of humans, and cant be readily fixed
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Actual differences in the time required for the object to travel the same distance.
What do you think you could do about the uncertainty due to this factor?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
There will always be some discrepencies in data, meaning that the values will not always be the same every time. this difference is more a measure of the sum of allthe other errors, contributing to one overall measurable error. By minimizing the other errors, this number will also be minimized.
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Differences in positioning the object prior to release.
What do you think you could do about the uncertainty due to this factor?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
To ensure positioning, the student might mark the spot in which they are putting the ball, or create a device that held the ball in the exact same spot. By ensuring the positioning was the same, the student will allbut eliminate that factor of error in the experiment.
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Human uncertainty in observing exactly when the object reached the end of the incline.
What do you think you could do about the uncertainty due to this factor?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
Although this doesnt contribute greatly to the outcome of the experiment, the student might make sure they are positioned in the same observation position for every trial to make sure that the perception does not change every time.
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&#Your work looks good. Let me know if you have any questions. &#
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