Query 1

course Phy 121

Tuesday August 11 at 2:15

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

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Your solution:

One takes the differences between the averages and squares them. Then they add up the squared numbers and divide by one less than the amount of squared numbers if the amount of numbers is not over 30. This amount is the standard deviation.

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 one plots a line of best fit there will always be uncertainties in the answer. The reason is because to do so one must estimate the central line of the graph visually; meaning with human error there will always be mistakes.

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 which an object is moving relative to time. For example 50 cm / second or 34 m/h

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:

Multiply the average speed by the time. For example 50 cm / second for 23 seconds is 23 * 50 which equals 1150 cm.

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:

Divide the distance by the average speed. For example, 30 cm at a speed of 5 cm / second is 30/5 or 6 seconds.

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 interval. For example 100ft in 50 seconds is 100 / 50 which equals 2ft / second.

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. &#