initial timing experiment

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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Initial Timing Experiment

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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).

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.

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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My setup was 1 CD case laying on a table top propping one end of a textbook. The cd case was 9mm in height, and the textbook used was CompTIA A+ Guide to Hardware, 4th Editon, ISBN 0619217626. The object that I rolled was a partially used tube of ChapStick Lip Balm. The tube of lip balm rolled straight and consistently, and seemed to pick up momentum towards the end of the book. I made sure during the the setup for both sets of trials that the cd case propping the book up not extended further than the where the edge of the cover meets the pages about 3mm in from the edge of the book. The length of the cover was 282mm and the top end of the book was at a height of 43mm and the bottom end of the book was at a height of 34mm.

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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 timed the interval it took the roll of Chap Stick to travel the distance of 282mm by releasing it with my left hand and simultaneously starting the timer with my right, I would then watch it travel to the edge of the book, and then hit the timer button again to get the interval. In the first set of time trials, the following times were measured:

#1-2.078125s

#2-2.0625s

#3-2.03125s

Then the setup was rotated 180 degrees, and the following times were mesaured in the second set of time trials:

#1-2.28125s

#2-2.121875s

#3-2.078125s

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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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Average time for time trial #1 2.0572s - 282mm, divide cm by the time, 2.82cm/2.0572s=1.37cm, or 137mm per second.

Average time for time trial #2 2.1604s - 282mm divide cm by the time, 2.82cm/2.1604s=1.31cm, or 131mm per second.

I believe that I got accurate measurments the entire time, but I am not sure how accurate I was a simultaneously releasing and starting the timer on at the exact same moment on each trial. As far as the average speed, I can only say its accurate to the amount of the least amount of significant digits of the variables given, which was 3 for the book length.

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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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The experiment would be nearly identical as above, but measure the time it takes from the beginning to the first half of the book, then from the second half to the edge of the book. If there was acceleration, than the first half time would be slower than the time it takes to complete the second half. Several time trials showed that it took about 1.6 seconds to reach the first half of the book, then about one-third of that to complete the second half of the distance.

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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: 

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Start952pm-endtime 1104pm, 72minutes

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You may add optional comments and/or questions in the box below.

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Your work looks very good. Let me know if you have any questions. &#

Note that if you submitted a Pearl Pendulum experiment, I have an unidentified version immediately following yours. I don't think you're at this point yet; let me know if the experiment is yours.