Assignment 0 query0

course Phy201

I believe this was everything, it doesn't seem to be everything we did though?

}Qbߜ\assignment #000

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000. `Query 0

Physics I

06-16-2008

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20:06:22

The Query program normally asks you questions about assigned problems and class notes, in question-answer-self-critique format. Since Assignments 0 and 1 consist mostly of lab-related activities, most of the questions on these queries will be related to your labs and will be in open-ended in form, without given solutions, and will not require self-critique.

The purpose of this Query is to gauge your understanding of some basic ideas about motion and timing, and some procedures to be used throughout the course in analyzing our observations. Answer these questions to the best of your ability. If you encounter difficulties, the instructor's response to this first Query will be designed to help you clarify anything you don't understand. {}{}Respond by stating the purpose of this first Query, as you currently understand it.

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RESPONSE -->

The purpose of this first Query is to guage our understanding of the basic ideas about motion and timing.

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20:07:40

If, as in the object-down-an-incline experiment, you know the distance an object rolls down an incline and the time required, explain how you will use this information to find the object 's average speed on the incline.

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RESPONSE -->

You can use the Average velocity formula, average speed equals the distance traveled divided by the time elasped.

confidence assessment: 2

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20:10:00

If an object travels 40 centimeters down an incline in 5 seconds then what is its average velocity on the incline? Explain how your answer is connected to your experience.

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RESPONSE -->

The objects' average velocity is 8 cm/s. It resembles the experiment that we conducted using an object that rolls and a flat surface, in which i used my textbook and ball of thread. Its also the same formula that was the answer in the last question.

confidence assessment: 2

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20:18:21

Using the same type of setup you used for the first object-down-an-incline lab, if the computer timer indicates that on five trials the times of an object down an incline are 2.42 sec, 2.56 sec, 2.38 sec, 2.47 sec and 2.31 sec, then to what extent do you think the discrepancies could be explained by each of thefollowing: {}{}a. The lack of precision of the TIMER program{}{}b. The uncertain precision of human triggering (uncertainty associated with an actual human finger on a computer mouse){}{}c. Actual differences in the time required for the object to travel the same distance.{}{}d. Differences in positioningthe object prior to release.{}{}e. Human uncertainty in observing exactly when the object reached the end of the incline.

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RESPONSE -->

The average velocity on the first half is 6.66 cm/s, and the second half is 4 cm/s.

I believer the answer is b. , because as a human we cannot precisely click the mouse the same each time.

confidence assessment: 1

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20:23:07

How much uncertainty do you think each of the following would actually contribute to the uncertainty in timing a number of trials for the object-down-an-incline lab? {}{}a. The lack of precision of the TIMER program{}{}b. The uncertain precision of human triggering (uncertainty associated bLine$(lineCount) =with an actual human finger on a computer mouse){}{}c. Actual differences in the time required for the object to travel the same distance.{}{}d. Differences in positioning the object prior to release.{}{}e. Human uncertainty in observing exactly when the object reached the end of the incline.

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RESPONSE -->

A. That is not going to make a big difference ove the long haul...because the timer program is not off in seconds but merely tenth or hundredths of a second.

B. Human error i believe can possibly be the greatest in this experiment. The letting go of the object that rolls down the incline, and the starting and stopping of the timer.

C. This shouldn't be much different. It is the same distance traveled on that surface and same object traveling the distance.

D. This could be a factor also, starting at one corner of the book and having the object travel to the far corner would increase the distance traveled, therefore causing a longer time.

E. Again, this is Human Error. I believe this single part causes the majority of the errors in this experiment. Its too many variable to control to be exactly precise in the experiment.

confidence assessment: 2

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20:27:47

What, if anything, could you do about the uncertainty due to each of the following? Address each specifically. {}{}a. The lack of precision of the TIMER program{}{}b. The uncertain precision of human triggering (uncertainty associated with an actual human finger on a computer mouse){}{}c. Actualdifferences in the time required for the object to travel the same distance.{}{}d. Differences in positioning the object prior to release.{}{}e. Human uncertainty in observing exactly when the object reached the end of the incline.

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RESPONSE -->

A. You could write the program differently for the Time Program. Adjusting in the program were the timer program decides to round off and its carry bits.

B. Have a laser sensor at the starting and stopping line, so when the object crosses the laser the timer starts and on the other end when the object crosses the other laser the timer stops.

C. I dont' see that happening if the same object is being used on the same surface at the same incline.

D. Develop some form of latch or lever that consistently lets the object roll off at a standard rate of time.

E. Goes along with my answer in B. Have a laser sensor at the starting and stopping line, so when the object crosses the laser the timer starts and on the other end when the object crosses the other laser the timer stops.

confidence assessment: 2

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20:34:33

According to the results of your introductory pendulum experiment, do you think doubling the length of the pendulum will result in half the frequency (frequency can be thought of as the number of cycles per minute), more than half or less than half?

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RESPONSE -->

I believer that you would have to answer when doubling the length you decrease the frequency by more than half.

confidence assessment: 1

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20:37:02

Note that for a graph of y vs. x, a point on the x axis has y coordinate zero and a point on the y axis has x coordinate zero. In your own words explain why this is so.

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RESPONSE -->

It's a typical frequency curve, the more cycles the less time or distance traveled, and as the speed intensifies or longer distances the less amount of cycles are going to occur in that time frame.

confidence assessment: 2

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20:45:00

On a graph of frequency vs. pendulum length (where frequency is on the vertical axis and length on the horizontal), what would it mean for the graph to intersect the vertical axis (i.e., what would it mean, in terms of the pendulum and its behavior, if the line or curve representing frequency vs. length goes through the vertical axis)? What would this tell you about the length and frequency of the pendulum?

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RESPONSE -->

If the results indicated that the graph intersected the y axis, i believe something must be incorrect. This would mean that the Length went into the negative or some kind of phase shift in the frequecny maybe. The motion of the pendulum may have got off frequency. I dont' really understand this question?

confidence assessment: 0

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20:46:55

On a graph of frequency vs. pendulum length, what would it mean for the graph to intersect the horizontal axis (i.e., what would it mean, in terms of the pendulum and its behavior, if the line or curve representing frequency vs. length goes through the horizontal axis)? What would this tell you about the length and frequency of the pendulum?

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RESPONSE -->

To me if the graph crossed the horizontal axis it would lead me to believe that frequency was very slow (not many cycles occuring) and the length of the pendulum was very large.

confidence assessment: 2

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20:47:54

If a ball rolls down between two points with an average velocity of 6 cm / sec, and if it takes 5 sec between the points, then how far apart are the points?

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RESPONSE -->

30 cm

confidence assessment: 2

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20:50:44

On the average the ball moves 6 centimeters every second, so in 5 seconds it will move 30 cm. {}{}The formal calculation goes like this: {}{}We know that vAve = `ds / `dt, where vAve is ave velocity, `ds is displacement and `dt is the time interval. {}It follows by algebraic rearrangement that `ds = vAve * `dt.{}We are told that vAve = 6 cm / sec and `dt = 5 sec. It therefore follows that{}{}`ds = 6 cm / sec * 5 sec = 30 (cm / sec) * sec = 30 cm.{}{}The details of the algebraic rearrangement are asfollows:{}{}vAve = `ds / `dt. We multiply both sides of the equation by `dt:{}vAve * `dt = `ds / `dt * `dt. We simplify to obtain{}vAve * `dt = `ds, which we then write as{}`ds = vAve *`dt.{}{}Be sure to address anything you do not fully understand in your self-critique.

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RESPONSE -->

I understood the concept of the question and answered the question correctly. I didn't do the equation algebraicly, but I did understand why I got the answer i did.

self critique assessment: 3

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20:57:08

You were asked to read the text and some of the problems at the end of the section. Tell me about something in the text you understood up to a point but didn't understand fully. Explain what you did understand, and ask the best question you can about what you didn't understand.

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RESPONSE -->

I didn't really understand the concept of dimensional analysis and how to figure them out with the dimensional check. I did understand the majority of the chapter. Some parts of the Significant figures was a little different to me. I know how to round, but when we talk about to the 4th significant figure i sometimes mess up or am not reading thru thorough.

confidence assessment: 1

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21:00:41

Tell me about something in the problems you understand up to a point but don't fully understand. Explain what you did understand, and ask the best question you can about what you didn't understand.

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RESPONSE -->

I did ok on most of the questions, but i had to go back through them and work them out a couple of times. I think this first chapter was a good building block on the chapters to come.

confidence assessment: 2

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Good work. We will continue to revisit the ideas of significant figures, dimensional calculations, error estimates, etc. throughout the course. These things are worth looking at early in the course, but they become easier to understand as we develop more of a context within which to understand them.