ph1 query 1

course Phy 121

June 25, 2009 about 9:20 pm

ph1 query 1*********************************************

Question: `qExplain in your own words how the standard deviation of a set of numbers is calculated.

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Your solution:

In order to get the standard deviation , we first add them up and then divide to get the average squared deviation. Once we have that we take the square root of that result and that is our standard deviation.

Confidence Assessment: 3

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Question: 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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Your solution:

Two people might obtain different results from the slope, because they could pick two different points on the line to obtain their slope from, they also might get a different y-intercept, because they pick different points on the line as well.

Confidence Assessment: 3

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Question: Briefly state what you think velocity is and how you think it is an example of a rate.

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Your solution:

I think velocity is the change in the position of an object divided by the change in clock time. It is an example of rate because rate is the change in something divided by something else. For example if you work 5 hours and make 25 dollars then you make 5 dollars an hour.

Confidence Assessment: 3

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Given Solution:

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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Self-critique (if necessary): OK

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Question: Given average speed and time interval how do you find distance moved?

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Your solution:

Average speed times time interval= distance moved

Confidence Assessment: 3

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Given Solution:

** You multiply average speed * time interval to find distance moved.

For example, 50 miles / hour * 3 hours = 150 miles. **

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Self-critique (if necessary): OK

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Question: Given average speed and distance moved how do you find the corresponding time interval?

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Your solution:

Distance moved/average speed

Confidence Assessment: 3

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Given Solution:

** 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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Self-critique (if necessary): OK

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Question: Given time interval and distance moved how do you get average speed?

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Your solution:

Distance moved/time interval=average speed

Confidence Assessment:

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Given Solution:

** 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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&#Good responses. See my notes and let me know if you have questions. &#