ph1query1

course Phy 121

1/30/10 at 5:50 p.m.

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 the beginning number and the next number and then subtract to find the difference; the absolute value of this

difference will be the standard deviation. All deviations are calculated using the beginning number and subtracting the other

numbers then taking absolute value.

confidence rating #$&*: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:

When fitting a straight line to a graph, it is tricky for me and differing results would probably happen for me if I did the same

problem twice. One eyeballs and tries to fit a string into the middle of the data without really intercepting any of the points.

confidence rating #$&*: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:

I think velocity is distance divided by time. I guess it is an example of a rate because one looks at changes in the data to

truly determine it, and it varies and is not constant.

confidence rating #$&*:1

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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 said this just in different words really.

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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 will give us distance traveled in a certain amount of time. If we know the time interval that has passed, we can

set up an equation to determine the distance. For example, if a car is moving at 25m/hr and has been traveling for 3 hrs, we can

estimate the miles traveled to be 75.

confidence rating #$&*:

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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:

If given average speed for example 20 m/hr and then given the distance of 60 miles, we can solve using an equation and figure out

that the car has traveled for 3 hours. 20(x) = 60

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:

distance divided by time

confidence rating #$&*:

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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. &#