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 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 instructors expectations. Comment on your experience with the three lab exercises you encountered in this assignment or in recent assignments. The 3 lab exercises that I encountered earlier were interesting and different at the same time. I thought the exercises made a big difference in helping me see physics in a fascinating perspective instead of timid point of view. ********************************************* 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 TIMER programs are usually accurate, but there could have been a flaw with the computer timer. #$&* The uncertain precision of human triggering (uncertainty associated with an actual human finger on a computer mouse) To what extent to you think the discrepancies are explained by this factor? your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv I believe the user of the TIMER program can cause a bigger flaw than the actual timer itself. No one is perfect with pressing a button to calculate the movement of objects. #$&* 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 Again measuring a time an object travels down the same distance will not be the same every time. Errors will happen in the measurement and timing. #$&* Differences in positioning the object prior to release. To what extent to you think the discrepancies are explained by this factor? your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv I can see many errors happening each time a person positions an object that is to be measured. Unless the object is put into a tight-fixed location, errors in perfection will happen every time. #$&* 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 We are bound to make mistake every time we observe the location at which an object stops. If that was a class experiment itself we will be amazed at how many different distances the class will come up with. #$&* ********************************************* Question: How much uncertainty do you think each of the following would actually contribute to the uncertainty in timing a number of trials for the ball-down-an-incline lab? The lack of precision of the TIMER program. To what extent to you think this factor would contribute to the uncertainty? your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv I believe the lack of precision contributed to 5 % of the uncertainties. #$&* 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 I believe the human triggering contributed to 10 % of the uncertainties. #$&* Actual differences in the time required for the object to travel the same distance. To what extent to you think this factor would contribute to the uncertainty? your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv I believe measuring the actual distance errors contributed to 5 % of the uncertainties. #$&* Differences in positioning the object prior to release. To what extent to you think this factor would contribute to the uncertainty? your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv I believe the differences in positioning the object contributed to 10 % of the uncertainties. #$&* Human uncertainty in observing exactly when the object reached the end of the incline. To what extent to you think this factor would contribute to the uncertainty? your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv I believe human uncertainty in observing contributed to 10 % of the uncertainties. #$&* ********************************************* 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 I would have used a TIMER program that was more accurate. #$&* The uncertain precision of human triggering (uncertainty associated with an actual human finger on a computer mouse) What do you think you could do about the uncertainty due to this factor? your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv I would have practice a little with pressing the mouse to improve with human triggering, not that it would have stopped all errors. #$&* 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 would have watched more closely to the timing to lessen the error in timing. #$&* Differences in positioning the object prior to release. What do you think you could do about the uncertainty due to this factor? your answer: vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv I know I mentioned earlier about positioning the object in a tight-fixed location. Now I realize that would change the outcome of the experiment altogether. #$&* 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 I would have observed more closely to the object and location. #$&* "