open query assn1

course Phy231

2/6/10 8pm

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:

You square all the deviations, add them together, divide by one less than the number of deviations, and then take the square root.

confidence rating #$&*: 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:

When fitting a straight line to the graph you have to put the line where the point will have the least amount of deviation. Doing this might mean not having the line touch a point on the graph at all. Because this is a best fit opinion is why it could be different from different people. This goes the same for the y-intercept, either you use the actual line if it goes through the y-axis or use a couple of points on the graph to find the slope and then use one of those points to find the y-intercept.

confidence rating #$&*: 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: Velocity is the rate of change of position which you would get by dividing the change in position by the clocked time.

A rate is a change in something divided by a change in something else, for example, change in A/change in B

confidence rating #$&*: 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: You would multiply the average speed by the time traveled and that would give you the distance moved.

confidence rating #$&*: 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: You would divide the distance moved by the average speed and it will give you the time interval.

confidence rating #$&*: 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: You divide the distance by the time interval and it will give you the average speed.

confidence rating #$&*: 3

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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. **

&#This looks good. Let me know if you have any questions. &#