Physics I 07-15-2008
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18:58:57 The Query program normally asks you questions about assigned problems and class notes, in question-answer-self-critique format. Since Assignments 0 and 1 consist mostly of lab-related activities, most of the questions on these queries will be related to your labs and will be in open-ended in form, without given solutions, and will not require self-critique. The purpose of this Query is to gauge your understanding of some basic ideas about motion and timing, and some procedures to be used throughout the course in analyzing our observations. Answer these questions to the best of your ability. If you encounter difficulties, the instructor's response to this first Query will be designed to help you clarify anything you don't understand. {}{}Respond by stating the purpose of this first Query, as you currently understand it.
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RESPONSE --> As I currently understand it, the purpose of this Query is to gauge my understanding of some basic ideas about motion, timing, and procedures to be used throughout the course to analyze my observations.
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19:17:10 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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RESPONSE --> Ave. speed = distance traveled/time elapsed, so I would plug the numbers into the formula and solve. confidence assessment: 3
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19:22:56 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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RESPONSE --> Ave. vel. = displacement/time elapsed = 40/5 = 8cm/s I examined speed/velocity in the ""Ball Down a Ramp"" experiment. confidence assessment: 3
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19:58:08 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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RESPONSE --> Ave. vel. for the first half of the incline = 20/3 = 6.7cm/s Ave. vel. for the second half of the incline = 20/2 = 10cm/s confidence assessment: 3
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21:04:22 Using the same type of setup you used for the first object-down-an-incline lab, if the computer timer indicates that on five trials the times of an object down an incline are 2.42 sec, 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 thefollowing: {}{}a. The lack of precision of the TIMER program{}{}b. The uncertain precision of human triggering (uncertainty associated with an actual human finger on a computer mouse){}{}c. Actual differences in the time required for the object to travel the same distance.{}{}d. Differences in positioningthe object prior to release.{}{}e. Human uncertainty in observing exactly when the object reached the end of the incline.
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RESPONSE --> I think the discrepancies could be explained mostly by the following (listed in order from causes the greatest discrepancy to causes the least discrepancy): 1. Human uncertainty in observing exactly when the object reached the end of the incline. (e) 2. The uncertain precision of human triggering (uncertainty associated with an actual human finger on a computer mouse). (b) 3. Differences in positioningthe object prior to release. (d) 4. The lack of precision of the TIMER program. (a) 5. Actual differences in the time required for the object to travel the same distance. (c) confidence assessment: 2
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21:33:57 How much uncertainty do you think each of the following would actually contribute to the uncertainty in timing a number of trials for the object-down-an-incline lab? {}{}a. The lack of precision of the TIMER program{}{}b. The uncertain precision of human triggering (uncertainty associated bLine$(lineCount) =with an actual human finger on a computer mouse){}{}c. Actual differences in the time required for the object to travel the same distance.{}{}d. Differences in positioning the object prior to release.{}{}e. Human uncertainty in observing exactly when the object reached the end of the incline.
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RESPONSE --> How much uncertainty do you think each of the following would actually contribute to the uncertainty in timing a number of trials for the object-down-an-incline lab? a. The lack of precision of the TIMER program. +/- 0.005 b. The uncertain precision of human triggering (uncertainty associated bLine$(lineCount) =with an actual human finger on a computer mouse). +/- 0.01 c. Actual differences in the time required for the object to travel the same distance. +/- 0.001 d. Differences in positioning the object prior to release. +/- 0.002 e. Human uncertainty in observing exactly when the object reached the end of the incline. +/- 0.025 confidence assessment: 1
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22:05:56 What, if anything, could you do about the uncertainty due to each of the following? Address each specifically. {}{}a. The lack of precision of the TIMER program{}{}b. The uncertain precision of human triggering (uncertainty associated with an actual human finger on a computer mouse){}{}c. Actualdifferences in the time required for the object to travel the same distance.{}{}d. Differences in positioning the object prior to release.{}{}e. Human uncertainty in observing exactly when the object reached the end of the incline.
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RESPONSE --> What, if anything, could you do about the uncertainty due to each of the following? Address each specifically. a. The lack of precision of the TIMER program. Use a timer program that is more accurate and precise. b. The uncertain precision of human triggering (uncertainty associated with an actual human finger on a computer mouse). Use an electronic release mechanism that is linked to a computer and timer program. c. Actual differences in the time required for the object to travel the same distance. Not much can be done here. It is what it is, so to speak. d. Differences in positioning the object prior to release. Use an electronic release mechanism that is secured and stable. e. Human uncertainty in observing exactly when the object reached the end of the incline. Use high speed cameras and sensors linked to the computer and timer program. confidence assessment: 2
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22:41:36 According 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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RESPONSE --> I think doubling the length of the pendulum will result in more than half the frequency. confidence assessment: 2
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00:03:39 Note 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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RESPONSE --> I'm not sure about this question. confidence assessment: 0
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?????????x???assignment #000 000. `Query 0 Physics I 07-18-2008
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17:59:35 Note 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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RESPONSE --> In the Cartesian plane, this is the origin. In the pendulum lab, assuming that the simple pendulum undergoes SHM, frequency (f) and period (T) are reciprocal functions of each other, and since T is dependent upon pendulum length (L), as L decreases, T decreases and f increases. If the L goes to zero, then so does the T. However, the f is undefined and never crosses the y axis. The larger the L, the larger the T and the smaller the f. No matter how large T becomes, f will not go to zero and will not intersect the x axis. So, for a graph of pendulum f versus T there is no point on the x axis where the y coordinate is zero and vice versa. confidence assessment: 1
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18:31:08 On 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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RESPONSE --> Pendulum length would be zero and the freq. would be at a maximum. confidence assessment: 1
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18:32:59 On 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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RESPONSE --> The pendulum L would be at a maximum and the freq. would be zero. confidence assessment: 1
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18:45:06 If 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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RESPONSE --> Every sec. (as an average) the ball moves 6 cm, so in 5 sec. it will move 30 cm between the two points. confidence assessment: 3
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18:48:50 On the average the ball moves 6 centimeters every second, so in 5 seconds it will move 30 cm. {}{}The formal calculation goes like this: {}{}We know that vAve = `ds / `dt, where vAve is ave velocity, `ds is displacement and `dt is the time interval. {}It follows by algebraic rearrangement that `ds = vAve * `dt.{}We are told that vAve = 6 cm / sec and `dt = 5 sec. It therefore follows that{}{}`ds = 6 cm / sec * 5 sec = 30 (cm / sec) * sec = 30 cm.{}{}The details of the algebraic rearrangement are asfollows:{}{}vAve = `ds / `dt. We multiply both sides of the equation by `dt:{}vAve * `dt = `ds / `dt * `dt. We simplify to obtain{}vAve * `dt = `ds, which we then write as{}`ds = vAve *`dt.{}{}Be sure to address anything you do not fully understand in your self-critique.
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RESPONSE --> I understand. Solve the formula for displacement (`ds). self critique assessment: 1
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18:55:35 You were asked to read the text and some of the problems at the end of the section. Tell me 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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RESPONSE --> I believe that I understood the content of the entire chapter. However, this is not to say that I will remember everything on a test or will not make a mistake on a problem as it relates to the material of chapter one. confidence assessment: 2
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??????v?q??? assignment #000 000. `Query 0 Physics I 07-19-2008
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16:07:22 Tell me about something in the problems you understand up to a point but don't fully understand. Explain what you did understand, and ask the best question you can about what you didn't understand.
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RESPONSE --> I think I understand the basics of absolute, estimated, and percent uncertainty, but I need a refresher when it comes to calculations and uncertainty. Take Chapter 1 problems 10 and 11 for example. I know how to solve the problems and give the answer in scientific notation, but I'm not sure of the determination of the uncertainty in each problem. In number 10, is the approx. uncert. +/- 2*10^3cm^2? In number 11, is the uncertainty calculated as follows? % Uncert. = [(0.09/2.86)*3]*100 = (0.03146853*3)*100 = (0.03*3)*100 = 0.09*100 = 9 confidence assessment: 1