#$&*
PHY 201
Your 'initial timing experiment' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** Initial Timing Experiment_labelMessages **
6/8 at 4:35 pm
** **
•Follow the instructions, fill in your data and the results of your analysis in the given format.
•Regularly save your document to your computer as you work.
•When you have completed your work:
Copy the document into a text editor (e.g., Notepad; but NOT into a word processor or html editor, e.g., NOT into Word or FrontPage).
Highlight the contents of the text editor, and copy and paste those contents into the indicated box at the end of this form.
Click the Submit button and save your form confirmation.
Note: The majority of student report taking less than an hour on this experiment, though a few report significantly longer times.
Take reasonable care to get good data in this experiment. Try to do the timing as accurately as possible. Measurements of length, height, etc. should be reasonably accurate (e.g., with a meter stick or ruler you can measure to withing +- 1 millimeter, but it's not necessary to try to determine fractions of a millimeter).
In this experiment you will use the TIMER program, a hardcover book, the toy car that came in your lab materials package (or, if you do not yet have the package, a cylinder or some other object that will roll along the book in a relatively straight line), and a ruler or the equivalent (if you don't have one, note the Rulers link, which is also given on the Assignments page).
•The book's cover should be straight and unbent.
•The toy car (or other object) should roll fairly smoothly.
Place the book on a flat level tabletop. You will prop one end of the book up a little bit, so that when it is released the object will roll without your assistance, gradually speeding up, from the propped-up end to the lower end. However don't prop the end up too much. It should take at least two seconds for the ball to roll down the length of the book when it is released from rest. For a typical book, a stack of two or three quarters placed under one end works well.
•Using the TIMER program determine how long it takes the ball to roll from one end of the ramp to the other, when released from rest. Once you've got the book set up, it takes only a few seconds to do a timing, so it won't take you long to time the object's motion at least three times.
•Determine how far the object travels as it rolls from its initial position (where you first click the timer) to its final position (where you click at the end of the interval). This will probably be a bit less than the length of the book, due to the length of the object itself.
•Determine how much higher one end of the book was than the other, and how far it is from the supports (e.g., the stack of quarters, or whatever you used to support one end) to the end of the book which rests on the table.
Then reverse the direction of the book on the tabletop, rotating the book an its supports (e.g., the stack of quarters) 180 degrees so that the ball will roll in exactly the opposite direction. Repeat your measurements.
In the box below describe your setup, being as specific as possible about the book used (title, ISBN) and the object being used (e.g., a can of vegetables (full or empty; should be specified) or a jar (again full or empty); anything round and smooth that will upon release roll fairly slowly down the incline), and what you used to prop the object up (be as specific as possible). Also describe how well the object rolled--did it roll smoothly, did it speed up and slow down, did it roll in a straight line or did its direction change somewhat?
your brief discussion/description/explanation:
The book used in this experiment is The Call to Write by John Trimbur, ISBN 9781139086148. The book measures 7.5 in. by 9.5 in. I used a 3 inch long piece of ½ in. PVC pipe to roll down the book. I used a small piece of wood to prop the book up on. The piece of wood is approx. 0.25 inches thick. The piped rolled smoothly and straight (after a few practice runs).
#$&* (note that your answer should always start in one of the blank lines preceding the #$&* mark)
In the space indicated below report your data. State exactly what was measured, how it was measured, how accurately you believe it was measured and of course what the measurements were. Try to organize your report so the reader can easily scan your data and identify any patterns or trends.
your brief discussion/description/explanation:
The end of the book that is propped up is about one-half inch higher than the other. I measured the time from when the pipe was “let go” at the top (propped up end) of the book until it stopped rolling, I labeled this, Time. I measured the length the pipe traveled in inched from the propped up end of the book to the stopping place, this is labeled, Length traveled. I repeated this process three times for each book placement.
Time Length Traveled
Run 1 2.1 sec 7.25 in
Run 2 2.4 sec 8.25 in.
Run 3 2.1 sec 7.75 in.
Book is rotated 180 degrees and all steps are repeated.
Run 1 2.3 sec 7.75 in
Run 2 2.4 sec 8 in.
Run 3 2.2 sec 7.5 in.
#$&*
Using your data determine how fast the object was moving, on the average, as it rolled down the incline. Estimate how accurately you believe you were able to determine the object's average speed, and give the best reasons you can for your estimate of the accuracy.
your brief discussion/description/explanation:
Time Distance Rate in movement
Run 1 2.1 sec 7.25 in .14 in/sec
Run 2 2.4 sec 8.25 in. .29 in/sec
Run 3 2.1 sec 7.75 in. .27 in/sec
@&
Your data don't vary all that much. From data this consistent you would not have a velocity of .14 in / sec and another velocity of .29 in / sec.
That was just a simple calculation error on your part. However I do expect you to look at your final results and see if they make sense in terms of the data.
*@
Book is rotated 180 degrees and all steps are repeated.
Run 1 2.3 sec 7.75 in .29 in/sec
Run 2 2.4 sec 8 in. .3 in/sec
Run 3 2.2 sec 7.5 in. .29 in/sec
I estimated the rate to hundredths of a second. My measurements of length traveled are rounded estimates. I think my data is not as precise as it could be but it is accurate.
#$&*
How fast was the object moving at the beginning of the timed interval?
According to your previous calculation, what was its average speed during this interval?
Do you think the object, when it reached the lower end of the book, was moving at a speed greater or less than the average speed you calculated?
your brief discussion/description/explanation:
.29 in/sec
Average speed is .23 in. per sec.
The pipe was moving faster than the average speed because it was rolling down an incline.
#$&*
List the following in order, from least to greatest. Indicate 'ties': The object's initial speed, its final speed, its average speed, and the change in its speed as it rolled from one end of the book to the other.
your brief discussion/description/explanation:
Initial speed .14 in/sec
@&
If the ball rolled from rest then its initial speed would have been 0.
*@
Average speed .23 in/sec
Final speed .27 in/sec
There is a .13 in/sec difference in the final and initial speed.
#$&*
Devise and conduct an experiment to determine whether or not the object is speeding up as it rolls down the incline. If you have set the experiment up as indicated, it should seem pretty obvious that the object is in fact speeding up. But figure out a way to use actual measurements to support your belief.
Explain how you designed and conducted your experiment, give your data and explain how your data support your conclusions.
your brief discussion/description/explanation:
Using the same “equipment” as the previous experiment, I will increase the height of the incline to determine if the speed of the pipe rolling down the incline increases.
This is the data:
Height Time Distance Rate of speed
.5 in 2.5sec 9 in .28 in/sec
.75 in 2.2 sec 10 in. .22 in/sec
1 in. 2.4sec 12 in .20 in/sec
The average rate of speed is .23 in/sec.
The greater the incline the greater the speed the pipe will roll down the incline.
#$&*
Your instructor is trying to gauge the typical time spent by students on these experiments. Please answer the following question as accurately as you can, understanding that your answer will be used only for the stated purpose and has no bearing on your grades:
Approximately how long did it take you to complete this experiment?
35 minutes
#$&*
You may also include optional comments and/or questions.
#$&*
*#&!
@&
You will need to revise your calculations of velocity. I've pointed out the contradiction in your calculation.
See also my other notes and please revise accordingly.
&#Please see my notes and submit a copy of this document with revisions, comments and/or questions, and mark your insertions with &&&& (please mark each insertion at the beginning and at the end).
Be sure to include the entire document, including my notes. &#
*@