assignment 0

course Phy 121

i'm not sure why questions about experiment 2 were on assignment 0, i didn't see any link saying to complete experiment 2, it was not on the due date link, i'm not sure when to complete the lab exercises

??}????^????~??assignment #000

000. `Query 0

Physics I

01-28-2009

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19:48:14

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 query program usually asks questions about assigned problems and class notes. assignments 0 and 1 consist of lab related work and no self-critique is needed. this query is set up to see your understanding of some basic concepts

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19:49:27

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 -->

average speed is distance traveled divided by total time

confidence assessment: 2

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assignment #000

000. `Query 0

Physics I

01-28-2009

??????x?????assignment #000

000. `Query 0

Physics I

01-28-2009

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20:23:54

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 -->

we are supposed to answer questions abouts lab experiments, i am lost no where in assignment 0 does it say do a lab experiment, i thought the assignment had to do with working problems 1-4 and 12-15 in chapter 1 of the text book, back to the query program it is set up to show the instructor your understanding of basic ideas of motion and timing and procedures to analyze our observations

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20:25:05

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 -->

average speed is distance divided by time

confidence assessment: 3

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20:28:07

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 -->

average velocity is displacement divided by time elapsed,

i'm not sure how the answer is connected to my experience, i'm not sure when i am supposed to do the labs, it doesn't give a due date at the due date link

confidence assessment: 2

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20:35:19

If the same object requires 3 second to reach the halfway point, what is its average velocity on the first half of the incline and what is its average velocity on the second half?

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RESPONSE -->

average velocity for the first half of the incline is delta x divided by delta t, 20m / 3s= 6.67 m/s

average velocity for the second half of the incline is 20m / 2s = 10m/s

confidence assessment: 2

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20:44:49

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 -->

a. it does say how accurate the time is, for example precise to .01sec

b. it is difficult to stop at the timer at exactly the same time each trial

c. is the incline the same on each trial

d. if the position of the object is released at different places on the incline, this would explain differences in time

e. the timer may have been stopped at different distances in attempts to observe where it actually get to the end of the incline

confidence assessment: 2

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20:55:04

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. the timer may not have been acurate contributing to different times

b. being unable to stop the timer at exactly the same time each trial would contribute a lot to the uncertainty in the timeing

c. this uncertainty may be caused by different slopes of the incline

d. this would contribute to major uncertainty because the object will be traveling different distances

e. if the object is not observed at exactly the end of the incline, the uncertainty will be high

confidence assessment: 1

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21:01:37

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. use a timer that is accurate to a given degree such as accurate to .01 second

b. there is always going to be human error associated with everything

c.

d. the object could be released at exactly the same point each trial

e. there will always be human error it will be difficult to watch the exact end of the incline

confidence assessment: 2

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21:04:09

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 -->

the frequency will be less than half

confidence assessment: 2

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21:09:44

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 -->

the points will be (X,0) and (Y,0)

i'm not sure if this is what the question asks

confidence assessment: 1

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21:13:42

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 -->

it would mean at some point the pendulum length would be zero, and the frequency would be number of cycles at the point of intersection

confidence assessment: 2

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21:17:03

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 -->

it would mean that the length of pendulm will be the point at which it intersects the x axis and the frequency would be near zero

confidence assessment: 1

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21:22:55

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 -->

delta x = ave velocity* delta t

delta x = 6cm/s * 5s

delta x = 30 cm

self critique assessment: 0

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21:29:19

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 understand a bit about significant figures, but it is difficult to know exactly how many significant figures there are in a given number

how do you determine the number of sigificant figures in numbers with zero such as 100 or 1.0908

converting units are at times difficult, is there a standard set of conversion factors

The number 100 has 1 significant figure. The number 100. has three significant figures. The way to express the number 100, accurate to two significant figures, is 1.0 * 10^2. The three-figure number 100. would be 1.00 * 10^2.

1.0908 would imply five significant figures.

The accepted way to write number when significant figures are important is in scientific notation. The significant figures are represented by a number not less than 1 and less than 10 (i.e., between 1 and 9.99999999... 9 , where the number of 9's represented by ... could be any positive integer), multiplied by the appropriate power of 10.

confidence assessment: 2

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21:32:59

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 -->

some of the conversions are difficult to change English units into SI, it is difficult to understand when to multiply and when to divide, it will be difficult to memorize the conversions for units such as hecto, nano, pico

confidence assessment: 2

Start with nano, micro, milli and kilo, mega and giga. If you know those you have a framework sufficient for tests in this course. You should know where to find the definitions of the others, but you don't need to memorize them.

You should also know that 1 inch = 2.54 cm (which is all you need to convert lengths, provided of course you know that a foot is 12 inches, a yard is 3 feet and a mile is 5280 feet), that a kilogram weighs about 2.2 pounds and that a liter of liquid water (which is a cube 10 cm on a side, which you should know) at a certain temperature (which you don't need to know) has a mass of 1 kg (this suffices to convert most liquid and volume measures, provided you know that there are 16 ounces in a pound, a pint is 32 ounces, a quart is 2 pints and a gallon is 4 quarts).

I might have left out something important, but if you know the above you can do most of the important conversions.

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The only experimental situations required to answer these are the Initial Timing Experiment (assigned as part of Asst 0) and the Pendulum Experiment (part of last week's assignment).

Your answers overall were fine. See my notes and let me know if you have additional questions.