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course Phy 232
7/1 1130 am
ph2 query 0
Most 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 differences in the times can be mostly explained by the lack of precision of the TIMER program. As seen through the TIMER experiment, the intervals are not always the same. All of the numbers seem to be close to each other, so part of the reason they are all different is because of the lack of precision. It is probably not fully the cause of the discrepancies, but it has a visible effect on the system.
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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
I think that the uncertain precision of human triggering could create a significant discrepancy if that is the cause. A human has a good chance of making an error in finger movement, and pressing the button either too soon or too late. If a number is off by a good amount then this is probably why.
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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
The actual differences in time required for the object to travel the same distance could be a slight cause, but usually if the same object is put under the same conditions, the outcome should be similar. I do not think this is the main cause of the discrepancies.
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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 differences in positioning of the objects prior to release could be a main factor in the discrepancies if this is the case. If an object is released further back, then it will take longer, so the time will be higher. This could be a major factor.
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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
Human uncertainty in observing exactly when the object reached the end of the incline could be another major factor in the discrepancies. It could create an small error if each trial is not stopped at exactly the same point, because then the ball might be rolling for a longer or shorter amount of time.
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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
This will always create uncertainty, since it was proven in the experiment that the TIMER program does not always have the same intervals.
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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: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
The uncertain precision of human triggering will create a little less uncertainty than the lack of precision of the timer.
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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
The actual differences in the time required for the object to travel the same distance will not contribute much to uncertainty because each object should take the same amount of time to travel, with other uncertainties creating the errors.
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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 could create a big uncertainty if we are unsure if the object is released in the exact same spot each time.
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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
This could create significant uncertainty if the exact spot where the ball reaches the end is not recorded each time. This would create an uncertainty of plus or minus a certain amount of time.
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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
There is not much you can do about this, since the TIMER program has a lack of precision and it will everytime. The problem is with the program, so there is nothing a human can do.
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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
The only thing that can be done about this uncertainty is to try to be precise as possible, but it impossible to fix all the way since there will always be uncertainty for the human finger.
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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
I think this is a small uncertainty, and the only thing that can be done is to make sure each object is completely the same, and under the same conditions.
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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 fix this uncertainty, the point at which the object is released must be marked and the human must make sure it is released at the same point each time.
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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
To fix this uncertainty relies on the skill of the human observing the object. It might make it easier to mark where the ""end"" is each time so the human can better see where to stop each time to make each interval closer.
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&#This looks good. Let me know if you have any questions. &#