#$&*
Phy 231
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.
** **
** **
Copy this document, from this point to the end, into a word processor or text editor.
¥ 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 was “Little Red Riding Hood” Classics for Beginning Readers printed by Reader’s Digest Young Readers, the object used was a heavy duty zinc chloride double A battery, to prop the book end up I used pennies placed in a row under the book edge 1 penny high. The battery rolled smoothly, speeding up as it went down the book, then slowing down shortly after leaving the book. The battery rolled in a pretty straight line with little deviation.
#$&* (note that your answer should always start in one of the blank lines preceding the #$&* mark)
In the space indicated below report your data. State exactly what was measured, how it was measured, how accurately you believe it was measured and of course what the measurements were. Try to organize your report so the reader can easily scan your data and identify any patterns or trends.
your brief discussion/description/explanation:
1st roll; initial time 1.666, stop time 10.633, dist. 64.3cm
2nd roll; initial time 1.569, stop time 10.103, dist. 62.4cm
3rd roll; initial time 1.15, stop time 8.785, dist. 60.5cm
180degrees
1st roll; initial time 4.773, stop time 10.123, dist. 47.5cm
2nd roll; initial time 1.194, stop time 6.865, dist. 49.5cm
3rd roll; initial time .946, stop time 6.684, dist. 44.3cm
#$&*
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:
I calculated the rate of change from each interval by dividing the distance, in cm, that the battery rolled by the time, in seconds, that it took for the battery to come to a stop after the initial time was taken. I then took the sum of those numbers and divided it by 6 to get an overall average of the rate, which I found to be 7.96cm/sec. The accuracy is not all that good considering the difference in the measurements taken at the initial location of the book and the measurements taken when the book and supports where rotated 180degrees.
#$&*
How fast was the object moving at the beginning of the timed interval?
According to your previous calculation, what was its average speed during this interval?
Do you think the object, when it reached the lower end of the book, was moving at a speed greater or less than the average speed you calculated?
your brief discussion/description/explanation:
I’m not sure how I’m suppose to get this answer without knowing what the position and time is at a point in the beginning of the timed interval. I do think that the object was moving at a greater speed as it reached the lower end of the book, greater than the average speed I calculated.
@& If the ball was released according to instructions, it would have started off with velocity zero.*@
#$&*
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:
1st roll; avg speed 7.17cm/sec
2nd roll; avg speed 7.31cm/sec
3rd roll; avg speed 7.92cm/sec
180degrees
1st roll; avg speed 8.88cm/sec
2nd roll; avg speed 8.73cm/sec
3rd roll; avg speed 7.72cm/sec
#$&*
Devise and conduct an experiment to determine whether or not the object is speeding up as it rolls down the incline. If you have set the experiment up as indicated, it should seem pretty obvious that the object is in fact speeding up. But figure out a way to use actual measurements to support your belief.
Explain how you designed and conducted your experiment, give your data and explain how your data support your conclusions.
your brief discussion/description/explanation:
I did it the same as above except that I clocked a time interval when the battery dropped off the book. So I ended up with 3 time measurements. The book is 20.9cm wide and I used that as a point to clock a time. I then calculated the rate when the battery was rolling on the book and then calculated the rate when it was off the book.
1st roll; initial time 1.037, end of book time 3.202, stop time 9.114, book rate 9.65cm/sec, off book rate 8.43cm/sec
2nd roll; initial time 2.0, end of book time 4.911, stop time 11.115, book rate 7.18cm/sec, off book rate 7.95cm/sec
The data does not confirm or deny my conclusion because the off book rate does not show the same conclusion in the 2 rolls. One shows that the rate is higher off the book than on the book, the other shows that the rate is lower off the book than on the book.
#$&*
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?
2 hours and 20 minutes
#$&*
&#Your work on this lab submission looks good. See my notes. Let me know if you have any questions.
Revision isn't requested, but if you do choose to submit revisions, clarifications or questions, please insert them into a copy of this document, 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. &#
After the 'Your Answer' prompt below, insert your answers to the following :
Describe how you constructed your pendulum and out of what (what you used for the mass, its approximate dimensions, what it is made of, what sort of string or thread you used--be as specific as possible).
Describe its motion, including an estimate (you don't have to measure this, just give a ballpark estimate) of how far it swung from side to side and how this distance varied over the time you counted.
Describe what you mean by a 'cycle'. Different people might mean different things, but there are only a couple of reasonable meanings. As long as you describe what you mean we will all understand what you measured.
'Frequency' means the number of cycles in a unit of time. Your counts are frequencies, in cycles/minute. 'Period' means time required for a cycle. Explain how you used your observed frequencies to obtain the periods of the nine pendulums in this experiment.
Your answer (start in the next line):
The pendulum was constructed of white sewing thread attached to a gold ring with a diameter of roughly 1.5 cm and a mass of roughly 15 grams.
The motion of the pendulum swung directly side-to-side at first and as it slowed began to form a slight elongated oval. As time went on, the distance traveled decreased.
A cycle is a measure of one full oscillation of the pendulum back and forth (swinging out and back to its origin).
A form of the frequency was found by counting the number of oscillations in 60 seconds. This was then used to determine the period, or how many seconds were required for a single oscillation cycle to take place on the pendulum. To do this, I divided 60 seconds by the number of cycles for each length.
#$&* explanations with std terminology
*#&!
@& Everything looks very good. Your graphs and your data show all the right trends.
I do have a question about the scale on which you measured the length. A pendulum of length about 10 inches or 25 cm would be expected to undergo 60 cycles in a minute, and it would be difficult to make a pendulum of this length differ much from this ideal result.
See my note and please submit a short note, along with a copy of this note, and clarify what you used to measure the lengths of your pendulums, and what the units were.
*@