ph1 query 1

course Phy 121

6/28 6:30

ph1 query 1*********************************************

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

Your solution:

The standard deviation is calculated by squaring each deviation, averaging them (adding them and dividing by one less than the total number of pieces of data), and taking the square root.

Confidence Assessment: 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:

In order to fit a straight line to a graph of y vs. x data, you would draw in a straight line that comes close to all points with about the same distance between each point and the line, and then find the rise, run, and slope of that line. To do this, you select two different points on your line and subtract Y1 from Y2 and X1 from X2 to find the rise and run, then divide those two numbers to get the slope. They can then be plugged into the equation y = mx + b where m = slope and b = y-intercept. This is an inexact process because you are confined by the units on the graph (i.e. it may be in whole units and you have to estimate to the .1 place) and it is estimation.

Confidence Assessment: 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:

I think that velocity is how fast an object is moving in a specific period of time. This is an example of a rate because it is a change in one variable (speed) divided by the change in another variable (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):

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

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Your solution:

The average rate of change of A with respect to B = (change in A) / (change in B). This can be manipulated into Average Speed = (change in distance) / (change in time) which results in Average Speed * (Change in Time) = (Change in distance).

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):

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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:

Average Speed = (Change in Distance) / (Change in Time)

Average Speed * Change in Time = Change in Distance

Change in Time = Change in Distance / Average 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):

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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 = (Change in Distance) / (Change in Time) or (Distance Moved) / (Time Interval)

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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&#Your work looks very good. Let me know if you have any questions. &#