course phy 121 The program cut me off and gave me an error message. I don't know if I finished all of the problems. άЍʞݡassignment #001
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22:00:37 Explain in your own words how the standard deviation of a set of numbers is calculuated.
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RESPONSE --> Obtain a set of data Obtain a random sample of the data. Calculate the mean for all of the data. Find the absolute value for the difference between each piece of data in your sample and the mean for all data. Square each of those results. Find the average of the squared numbers by: Adding up all of the squared results and dividing by 1 less than the number of pieces of data. Find the square root of the average. confidence assessment: 2
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22:04:16 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 --> Graph the data points. Using a thread or other straight line place a straight line on the graph and move it around until you think the straight line is as equally close to all the data points as possible. This procedure involves uncertainty because it is somewhat subjective. It involves just visually placing the line and is not based on objective information. Two people may feel that the line is better placed in different locations and therefore will obtain different results. confidence assessment: 2
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22:07:12 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 average rate that an object moves from one point in space to another point in space in a given amount of time. It is found by dividing the total displacment value by the time required to move that far. Rate is found by dividing a total quantity by the time required also. confidence assessment: 2
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22:08:43 ** 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 didn't specify the CHANGE in something, which is a better way of saying it. self critique assessment: 2
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22:09:56 Given average speed and time interval how do you find distance moved?
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RESPONSE --> dv = ds / dt dv * dt = ds ds = dv * dt confidence assessment: 2
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22:10:04 ** You multiply average speed * time interval to find distance moved. For example, 50 miles / hour * 3 hours = 150 miles. **
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RESPONSE --> self critique assessment: 3
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22:10:56 Given average speed and distance moved how do you find the corresponding time interval?
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RESPONSE --> dv = ds / dt dv * dt = ds dt = ds / dv confidence assessment: 2
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22:17:56 ** 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 dv instead of vAve. vAve is more accurate I suppose. I don't understand cm / (cm/s) = cm * s / cm = s I understand s = cm / (cm/s) it is the same as dt = ds / vAve but how does it equal cm*s/cm ? self critique assessment: 1
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22:19:13 Given time interval and distance moved how do you get average speed?
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RESPONSE --> vAve = ds / dt confidence assessment: 2
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22:19:32 ** 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 --> self critique assessment: 3
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