course Phy 201 krq찶N⯔~assignment #000
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20:05:34 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 --> Okay confidence assessment: 3
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Cyƥy|~ assignment #000 000. `Query 0 Physics I 05-19-2007
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20:07:18 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 --> The purpose of this query is to gauge one's undersatnding of motion, timing, and the questioning system in general.
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20:08:39 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 --> Speed is equivalent to distance/time; so, since we know the length (distance) of the incline, we can divide that by the time required, thus giving the speed. confidence assessment: 3
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20:12:22 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 --> V= chance in distance/change in time =40 cm-0cm (starting point)/ 5-0 (since we assume the clock started at 0) =40 cm/ 5 sec = 8 cm/ sec. I used the textbook, found the length and how long it took the chapstick to roll down the book and from this data was able to, using the above formula, calculate the average velocity. Of course, we later discovered that the velocity through the incline was not constant. confidence assessment: 3
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20:15:13 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 --> The average velocity on the first half would be calculated by dividing 20 (half of 40) by 3 (3 of 5 seconds). 20/3 = 6.7 cm/ sec The average velocity on the second half would be calculated by dividing 20 by 2 (the remainder of 5 after subtracting 3). 20/2 = 10 cm/ sec confidence assessment: 3
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20:17:31 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 would say all but c. C is a result of the other things (for instance, different positioning upon releasing the object). The discrepancies in the times otherwise, however, could be contributed to any or all of the other errors noted to the left. confidence assessment: 3
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21:02:28 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 --> a. It could contribute some uncertainty (only in terms of rounding). b. Human triggering could cause a LOT of error c. I do not think this is a direct cause but instead is a result of other things like positioning. It is possible, however, that the surface of the book could be different in certain spots, but that, again, is another cause in itself. d. This could definately cause differences in time (different angles, different surface textures in different spots, etc.). e. Same as B--the human eye is obviously not overly sufficient in making judgements down to the hundredths or thousandths of seconds. confidence assessment: 3
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21:04:36 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 --> A. Understand how the program works (I.e., that is it only accurate to the hundredth spot--after that, things are rounded) B. There is not much to do about this short of using a laser or robot that takes away the human aspect. C. Make sure the positioning is always the same, that the object is released at exactly the same place, etc. D. Mark exactly where to place the object upon release (instead of just ""eyeing"" it). E. Again, the only way to eliminate human error is to eliminate the human, whether it be with robots or lasers, etc. confidence assessment: 3
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21:07:56 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 --> According to my results, doubling the string length will result in more than half the frequency. After doubling (an estimated double) the string the first time, the frequency per minute went from 61 to 43 (more than half) and then after doubling the length again from 43 to 29 (again, more than half). It did decrease the frequency, but not as much as a whole fifty percent. confidence assessment: 3
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21:13:10 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 order for a point to lie on either the x or y axis, the axis on which the point does not lie must be zero; otherwise, the point would be between the two axes, not on one alone. For instance, the point (3,0) could only be on the x axis if y is 0; if y were 1, it would be impossible that the point would lie on the line (and vice versa). confidence assessment: 3
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21:16:53 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 --> For the line to go through the vertical axis, it would indicate that the length of the pendulum was at zero but that the frequency of the cycles was still existant (that is, that the pendulum has no length but that somehow the pendulum was still able to swing). confidence assessment: 3
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21:18:42 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 --> For the graph to intersect the horizontal axis, it would mean that the frequency of the pendulum swings has reached zero (that is, the pendulum is not swinging) although the pendulum could still have length. That is, the graph could have the coordinates (3,0), indicating that the pendulum length is 3 cm but that it has no frequency or movement at that point. confidence assessment: 3
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21:20:34 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 --> The points are 30 cm apart. Distance = rate/ time =(6 cm/sec)(5 sec) =30 cm confidence assessment: 3
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21:20:59 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 this fully. self critique assessment: 3
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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 --> At first, I did not understand Question number 5 about ""percent uncertainty."" But, I looked it up in the book and I understand that it is the ratio of the uncertainty to the measured valued and that number multiplied by 100. confidence assessment: 3
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