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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.
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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:
My book (PostSecret, by Frank Warren, ISBN: 978-0-06-089919-6) is 26.6 centimeters long. The lifted side is exactly 4 cm high, with another book to prop it up (The Lilies of the Field, by William E. Barrett, ISBN: 0-446-31500-1). Im using the Hot Wheel you sent meIts called the Fangula. It was born in 2009 in El Segundo, CA. It has an exposed engine, tall injector stacks, side pipes, a clear roof, and is said to be one killer ride. It also has a perfect gold and purple paintjob to represent my James Madison spirit.
The undeniably killer ride seems to glide relatively smoothly and in a straight path. The car sped up as it traveled.
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@& Very good. I saved that one.*@
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:
From left to right:
Trial 1 (from rest to falling off the end of the book; 26.6 cm): 2.574 seconds
Trial 2: 2.324 seconds
Trial 3: 2.586 seconds
From right to left:
Trial 1: 2.337 seconds
Trial 2: 2.335 seconds
Trial 3: 2.229 seconds
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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 think I am within .02 seconds. I tried to perfectly time releasing the car with my left hand and clicking the start timer button with my right, and stopping at exactly the same point of the car falling off of the book each time. I am confident in my accuracy at achieving this.
The object, on average, took about 2.398 seconds to roll down the incline.
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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:
If the object moved 26.6 cm in 2.398 seconds, on average, then the object was moving at an average rate of 11.1 cm/second (26.6 cm / 2.398 s). I believe the object was moving faster than this in the beginning, and slower than the estimated number as it reached the end of the book.
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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:
Change in speed
Final speed
Average speed
Initial speed
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@& Speed would start out at 0 and increase to a final speed. The change in speed would therefore be the final speed.
This might (or might not) make a difference in your ordering.*@
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 marked my large book at 13.3 cm (halfway point). I will stop the clock when the car reaches this point for the first half of the experiment and will do so for 3 trials. Next, I will conduct three trials where I start the timer when the car reaches the 13.3 cm point until the end. This way, the average top half speed can be compared to the average bottom half speed.
First half:
Trial 1: 0.881 seconds
Trial 2: 0.977 seconds
Trial 3: 0.917 seconds
Second half:
Trial 1: 1.239 seconds
Trial 2: 1.419 seconds
Trial 3: 1.156 seconds
The average first half speed was 0.925 seconds. Over 13.3 cm, the object was traveling 14.4 cm/second (13.3 cm / 0.925 seconds). The average second half speed was 1.27 seconds. Over 13.3 cm, the object was traveling 10.5 cm/second in the second half (13.3 cm / 1.27 seconds). The object, on average, is traveling about 3.9 cm/second faster in the first half of the trial.
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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?
About 30 minutes.
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You may also include optional comments and/or questions.
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*#&!
@& Well done. Do, however, be sure to see my notes*@