ph1 query 1

course PHY 121

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:

Take all the differences from the arithmetic mean of a set of number, calculated the square of these numbers, and then find the square rood of the mean which is the standard deviation.

Confidence Assessment: 2

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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:

Basically you are trying to fit the line between the points on the graph. There are many uncertaninties that can occur. No two people are going to line their string up the same way or even look at the same points on the chart.

Confidence Assessment: 2

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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 defined as speed with direction. And speed is the rate at which a distance is traveled in a certain amount of time.

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): I think I did an ok job of answering this one.

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

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Your solution:

If the average speed is 50 km/hour and the time is 2 hours, then you just multiply the time given by the speed to know that they object has traveled 100 km.

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:

Time interval = distance / average speed. So if you have traveled 20 km at 10 km/hr then you have been traveling for 2 hours. Just divide the distance by the 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: Average speed = distance / time change. 100 km / 2 hours would give you an average speed of 50 km/hr.

Confidence Assessment: 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. **

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