course PHY 121
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
#$&* The lack of precision of the timer program shows that it is accurate to a certain degree. In the example mention it is accurate up to about .2 second which gives an estimate of what the true precise time would be.#$&*
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
#$&* The reaction time of the person clicking on the mouse has a chance of fluctuating. Even when getting in a steady rhythm it is still quite easy for a person to miss a click or lose their rhythm. Or the mouse itself can have a delay when communication with the computer. #$&*
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
#$&* A discrepancy like this could only happen if events were changed from trial to trial. I find it unlikely that an object traveling the same distance under the same conditions would have a discrepancy in the time that it took to travel this distance.
Differences in positioning the object prior to release.
To what extent to you think the discrepancies are explained by this factor?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
#$&* the factor of positioning plays the largest factor in changes or discrepancies in time. When changing the position of the object prior to release, this can change many of factors like velocity, speed, and distance. By changing up all these factors there is bound to be a discrepancy in the times that it takes the object to travel.#$&*
Human uncertainty in observing exactly when the object reached the end of the incline.
To what extent to you think the discrepancies are explained by this factor?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
#$&* Reaction time and how well a person is focused on and paying attention to the positioning of the object are factors in the determination of when the object would reach the end of the incline. Therefore, precision would almost indefinitely be off in this case.#$&*
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Question: How much uncertainty do you think each of the following would actually contribute to the uncertainty in timing a number of trials for the ball-down-an-incline lab?
The lack of precision of the TIMER program.
To what extent to you think this factor would contribute to the uncertainty?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
#$&* It would give you a decent estimate of the times, but no tool is perfectly accurate so there would still be a marginal amount of uncertainty due to this factor.#$&*
The uncertain precision of human triggering (uncertainty associated with an actual human finger on a computer mouse)
To what extent to you think this factor would contribute to the uncertainty?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
#$&* This factor would play a very large role in uncertainty. There is a great chance in fluctuation of a humans reaction when clicking the mouse. There is no systematic or mechanical way to go about clicking the mouse to ensure that you are getting the same click each time so the uncertainty due to this factor is large.#$&*
Actual differences in the time required for the object to travel the same distance.
To what extent to you think this factor would contribute to the uncertainty?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
#$&* I find that this factor would have the least affect on time differences. An object under the same conditions and traveling the same distance, should basically have no differences in time therefore the uncertainty of this factor seems to be quite low.#$&*
Differences in positioning the object prior to release.
To what extent to you think this factor would contribute to the uncertainty?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
#$&* There would be uncertainty due to the changing of position of the object prior to release. In this case there would nearly always be a difference in time it took the object to travel. This would account for differences in time and the uncertainty with this would most likely result from not timing each position multiple times. Also when completely multiple trials you would have to be precise in your positioning, making sure to place them in the exact same place each time you repeat a trial of the same position. This would also take into account human error/ uncertainty again.#$&*
Human uncertainty in observing exactly when the object reached the end of the incline.
To what extent to you think this factor would contribute to the uncertainty?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
#$&* Human error in observation and reaction seem to be the biggest factor in discrepancy and uncertainty in any case. It is unlikely that a human would precisely and accurately observe the object reaching the end of the incline at the same exact time during multiple trials.#$&*
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Question: What, if anything, could you do about the uncertainty due to each of the following? Address each specifically.
The lack of precision of the TIMER program.
What do you think you could do about the uncertainty due to this factor?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
#$&* There is not much that could be done to change the uncertainty of this factor. No tool or program is indefinitely accurate so there will always be, to some degree or other, a lack of total accuracy and precision.#$&*
The uncertain precision of human triggering (uncertainty associated with an actual human finger on a computer mouse)
What do you think you could do about the uncertainty due to this factor?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
#$&* practice clicking many times to get yourself in a rhythm before actually doing an experiment.#$&*
Actual differences in the time required for the object to travel the same distance.
What do you think you could do about the uncertainty due to this factor?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
#$&* The only thing that could be done about uncertainty in this case, would be to make sure that the conditions in which the object are traveling in and the distance that it is traveling are the same for each trial. Otherwise, there shouldnt be any uncertainty due to this factor.#$&*
Differences in positioning the object prior to release.
What do you think you could do about the uncertainty due to this factor?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
#$&* Making sure that each time you change the positioning of the object, you document it and do a trial for each position multiple times would help to cut down on uncertainty.#$&*
Human uncertainty in observing exactly when the object reached the end of the incline.
What do you think you could do about the uncertainty due to this factor?
your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
#$&* To cut down on uncertainty is human observation, it would be best to complete this experiment in a place where there are no other distractions, ensuring that all your attention and focus is on the task at hand.#$&*
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Question: If, as in the object-down-an-incline experiment, you know the distance an object rolls down an incline and the time required, explain how you will use this information to find the object 's average speed on the incline.
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Your solution:
#$&*In this case, if you know the time as well as the distance, and for instance say the time is 30 seconds, and the distance is 60 cm, you divide the distance by the time which would give you an average speed of 2 cm per second.#$&*
confidence rating #$&* ok
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Question: If an object travels 40 centimeters down an incline in 5 seconds then what is its average velocity on the incline? Explain how your answer is connected to your experience.
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Your solution:
#$&* displacement = 40 cm (40 cm 0 cm = 40 cm)
elapsed time= 5 seconds.
Velocity = 40/5 = 8 cm / second
confidence rating #$&*: ok
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Question: If the same object requires 3 second to reach the halfway point, what is its average velocity on the first half of the incline and what is its average velocity on the second half?
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Your solution:
#$&* 1st half: displacement = 20 cm (20 cm 0 cm = 20 cm)
elapsed time= 3 seconds average
Velocity = 20 cm / 3 s = 6.7 cm / s
2nd half: displacement= 20 cm (40 cm 20 cm = 20 cm)
elapsed time= 2 seconds average
Velocity = 20 cm / 2 s = 10 cm / s
confidence rating #$&* ok
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Question: `qAccording to the results of your introductory pendulum experiment, do you think doubling the length of the pendulum will result in half the frequency (frequency can be thought of as the number of cycles per minute), more than half or less than half?
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Your solution:
#$&* it seems as though even if you double the length of your pendulum the frequency will be a little less than half.#$&*
confidence rating #$&*:
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Question: `qNote that for a graph of y vs. x, a point on the x axis has y coordinate zero and a point on the y axis has x coordinate zero. In your own words explain why this is so.
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Your solution:
#$&* When a point falls either on the x, or the y, axis it cannot be in any other position than zero on the alternate axis. Otherwise, the point would not lie exactly on either axis.#$&
confidence rating #$&* ok
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Question: `qOn a graph of frequency vs. pendulum length (where frequency is on the vertical axis and length on the horizontal), what would it mean for the graph to intersect the vertical axis (i.e., what would it mean, in terms of the pendulum and its behavior, if the line or curve representing frequency vs. length goes through the vertical axis)? What would this tell you about the length and frequency of the pendulum?
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Your solution:
#$&*This would mean at some point the length would have to be zero#$&*
confidence rating #$&*
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Question: `qOn a graph of frequency vs. pendulum length, what would it mean for the graph to intersect the horizontal axis (i.e., what would it mean, in terms of the pendulum and its behavior, if the line or curve representing frequency vs. length goes through the horizontal axis)? What would this tell you about the length and frequency of the pendulum?
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Your solution:
#$&*This would mean that at some point the frequency of the pendulum was zero.#$&*
confidence rating #$&* ok
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Question: `qIf a ball rolls down between two points with an average velocity of 6 cm / sec, and if it takes 5 sec between the points, then how far apart are the points?
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Your solution:
#$&* 6 * 5 = 30, which means that the 2 points were 30 cm apart. If the ball rolled 6 cm in 1 sec then you multiply 6 times the 5 seconds which would give you 30 cm in 5 seconds.#$&*
confidence rating #$&*:
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Question: `qYou were asked to read the text and some of the problems at the end of the section. Tell your instructor about something in the text you understood up to a point but didn't understand fully. Explain what you did understand, and ask the best question you can about what you didn't understand.
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Your solution:
#$&*I understand the text but While doing the exercises I had to read the questions few time before I understood what it was asking me. On some of the odd number questions I referred to the back of the book to make I was answering the questions right. If I didnt get it right I when back to the sections look for where I made my mistake.#$&*
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&#Very good work. Let me know if you have questions. &#
#$&*