course phy121 Physics I09-09-2008
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15:20:49 Explain in your own words how the standard deviation of a set of numbers is calculuated.
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RESPONSE --> You take a sample of the deviations you have in front of you. Determine the difference between them and the mean of the full list of deviations. Square this difference and add them together. Then divide by one less than the number of sample deviations you chose to get the standard deviation. confidence assessment: 1
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15:23:51 Explain in your own words the process of fitting a straight line to a graph of y vs. x data, and briefly discuss the nature of the uncertainties encountered in the process. For example, you might address the question of how two different people, given the same graph, might obtain different results for the slope and the vertical intercept.
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RESPONSE --> You use something such as a string or straight edge to find the line that best fits the data points. This can be very difficult and most people are not likely to get the line correct. Any two people are very unlikely to choose the same line, let alone the correct line. confidence assessment: 2
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15:24:39 Briefly state what you think velocity is and how you think it is an example of a rate.
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RESPONSE --> velocity is the rate of travel shown in distance/time. confidence assessment: 3
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15:25:04 ** A rate is a change in something divided by a change in something else. This question concerns velocity, which is the rate of change of position: change in position divided by change in clock time. **
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RESPONSE --> I stated that in a single sentence I believe. self critique assessment: 3
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15:25:54 Given average speed and time interval how do you find distance moved?
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RESPONSE --> multiply speed by time interval and it will give you the distance moved. 5mph * 2hrs = 10miles confidence assessment: 3
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15:26:15 ** You multiply average speed * time interval to find distance moved. For example, 50 miles / hour * 3 hours = 150 miles. **
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RESPONSE --> exactly how I put it. self critique assessment: 3
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15:27:03 Given average speed and distance moved how do you find the corresponding time interval?
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RESPONSE --> distance moved / average speed = time interval 150 miles / 50mph = 3 hrs confidence assessment: 3
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15:27:35 ** time interval = distance / average speed. For example if we travel 100 miles at 50 mph it takes 2 hours--we divide the distance by the speed. In symbols, if `ds = vAve * `dt then `dt = `ds/vAve. Also note that (cm/s ) / s = cm/s^2, not sec, whereas cm / (cm/s) = cm * s / cm = s, as appropriate in a calculation of `dt. **
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RESPONSE --> I used the math from your previous question. self critique assessment: 3
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15:28:16 Given time interval and distance moved how do you get average speed?
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RESPONSE --> distance moved / time interval = average speed 150 miles / 3hrs = 50mph confidence assessment: 3
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15:28:22 ** Average speed = distance / change in clock time. This is the definition of average speed. For example if we travel 300 miles in 5 hours we have been traveling at an average speed of 300 miles / 5 hours = 60 miles / hour. **
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RESPONSE --> got it! self critique assessment: 3
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course phy121 Physics I09-09-2008
......!!!!!!!!...................................
15:20:49 Explain in your own words how the standard deviation of a set of numbers is calculuated.
......!!!!!!!!...................................
RESPONSE --> You take a sample of the deviations you have in front of you. Determine the difference between them and the mean of the full list of deviations. Square this difference and add them together. Then divide by one less than the number of sample deviations you chose to get the standard deviation. confidence assessment: 1
.................................................
......!!!!!!!!...................................
15:23:51 Explain in your own words the process of fitting a straight line to a graph of y vs. x data, and briefly discuss the nature of the uncertainties encountered in the process. For example, you might address the question of how two different people, given the same graph, might obtain different results for the slope and the vertical intercept.
......!!!!!!!!...................................
RESPONSE --> You use something such as a string or straight edge to find the line that best fits the data points. This can be very difficult and most people are not likely to get the line correct. Any two people are very unlikely to choose the same line, let alone the correct line. confidence assessment: 2
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15:24:39 Briefly state what you think velocity is and how you think it is an example of a rate.
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RESPONSE --> velocity is the rate of travel shown in distance/time. confidence assessment: 3
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15:25:04 ** A rate is a change in something divided by a change in something else. This question concerns velocity, which is the rate of change of position: change in position divided by change in clock time. **
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RESPONSE --> I stated that in a single sentence I believe. self critique assessment: 3
.................................................
......!!!!!!!!...................................
15:25:54 Given average speed and time interval how do you find distance moved?
......!!!!!!!!...................................
RESPONSE --> multiply speed by time interval and it will give you the distance moved. 5mph * 2hrs = 10miles confidence assessment: 3
.................................................
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15:26:15 ** You multiply average speed * time interval to find distance moved. For example, 50 miles / hour * 3 hours = 150 miles. **
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RESPONSE --> exactly how I put it. self critique assessment: 3
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15:27:03 Given average speed and distance moved how do you find the corresponding time interval?
......!!!!!!!!...................................
RESPONSE --> distance moved / average speed = time interval 150 miles / 50mph = 3 hrs confidence assessment: 3
.................................................
......!!!!!!!!...................................
15:27:35 ** time interval = distance / average speed. For example if we travel 100 miles at 50 mph it takes 2 hours--we divide the distance by the speed. In symbols, if `ds = vAve * `dt then `dt = `ds/vAve. Also note that (cm/s ) / s = cm/s^2, not sec, whereas cm / (cm/s) = cm * s / cm = s, as appropriate in a calculation of `dt. **
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RESPONSE --> I used the math from your previous question. self critique assessment: 3
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15:28:16 Given time interval and distance moved how do you get average speed?
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RESPONSE --> distance moved / time interval = average speed 150 miles / 3hrs = 50mph confidence assessment: 3
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15:28:22 ** Average speed = distance / change in clock time. This is the definition of average speed. For example if we travel 300 miles in 5 hours we have been traveling at an average speed of 300 miles / 5 hours = 60 miles / hour. **
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RESPONSE --> got it! self critique assessment: 3
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