Assignment 1 Query

course PHY 201

2/3/10 around 11:00 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:

The standard deviation is calculated by finding the mean of the set of numbers. After you find the mean, then you calculate the deviation of the numbers from the mean. Once that is done then you calculate the squares of the deviations. You then find the mean of the squared deviations. Then you take the square root of the squared deviations.

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 you try to estimate the straight line going through the points at an average distance from each point. There are many uncertainties because you may not see it the same as someone else, your best fit line may not be someone else's best fit line.

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 in speed. It is a rate, because it is a measure of the change in distance over a certain time period.

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 multiply the average speed by the time interval.

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 divide the distance by the speed.

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.

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. **

&#Very good responses. Let me know if you have questions. &#