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.
** template formInitial Timing Experiment
You may enter any message or comment you wish in the box below:
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In this experiment you will use the TIMER program, a hardcover book, 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 on the Assignments page).
- The book's cover should be straight and unbent.
- The 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.
- 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. Time the object's motion at least five times.
- Determine how far the object actually travels as it rolls from one end to the other.
- Determine how much higher one end of the book was than the other, and how far it is from one end to the other.
Then reverse the direction of the book on the tabletop, rotating the book and its prop 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 solid glass marble, a small can of tomato paste (full or empty?), a ball-point pen), 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?
Note: Don't trust this form. Compose your answer in Notepad or a word processor, saving it every few minutes, then copy and paste it into the box. Power could surge, your computer could malfunction, in any of a number of ways the work you put into this form could be lost. Compose it elsewhere and keep a copy.
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I actually set this up on tile floor because it was more level than my desk. I used the book Calculus: Early Transcendentals 5e by James Steward, ISBN: 0-534-39321-7. The book is 26mm long. I propped it up with a Firefly dvd case which has a height of 7mm, elevating the book 7mm off the ground. The object I used to roll down the book was a can of Progresso Light Southwestern-Style Vegetable soup (diameter of 8mm) that was full and unopened. The object rolled smoothly down the slope and it kept a constant direction but sped up as it moved.
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In the box 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 see any patterns that might occur.
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I measured the length of the book (26mm) and the height of the object it was propped up with (7mm). I placed the can on the edge of the book so that the can was flush with the book. I believe my measurements to be fairly accurate.
My First Rolling Times:
1 1614.914 1614.914
2 1616.664 1.75
3 1621.641 4.976563
4 1623.539 1.898438
5 1628.75 5.210938
6 1630.547 1.796875
7 1635.789 5.242188
8 1637.477 1.6875
9 1642.602 5.125
10 1644.406 1.804688
11 1646.523 2.117188
12 1648.234 1.710938
My 2nd Rolling Times:
1 1813.297 1813.297
2 1814.969 1.671875
3 1819.563 4.59375
4 1821.242 1.679688
7 1828.086 2.015625
8 1829.727 1.640625
13 1843.367 2.71875
14 1844.945 1.578125
27 1983.313 13.9375
28 1984.898 1.585938
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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.
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The average speed from my recordings was 1.63125 seconds. 0.026 m / 1.63125s = 0.0159m/s. This might not be completely accurate as my times were close, but had differences, however I'm pretty confident about the distance it traveled each time.
I'll bet the book was 26 cm, not 26 mm. This would give you an average speed of about .159.
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Devise and concuct 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.
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I setup the experiment the same way it was before and took the time intervals between position 0 and 13, and from position 13 to 26 on the same roll and found the average velocities on those intervals. From position 0 to 13, the average time was 1.53 seconds. 0.013m/1.53s = .0085m/s on the first interval. On the second interval the average time was .711s so 0.013m/.711s = 0.018m/s. This is more than twice as fast as it was traveling on the first interval, proving that it indeed did speed up as it traveled down the slope.
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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?
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About 30 minutes.
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You may add optional comments and/or questions in the box below.
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Good work, but be sure to see my note about cm vs. mm.