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

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).

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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I began by propping up my Physics book, the 6th Edition Physics Giancoli (ISBN 0-13-060620) on a small stack of printer paper about 2 cm high. I used the small spool of black thread that came with the lab kit to roll from one side of the book to the other. The spool of thread was light in weight, even though it was full of thread, and was about 4 cm in length.

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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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The amount of time it took for the spool of thread to roll from one end of the book to the other was measured. It was measured in seconds and was quite accurate because the TIMER system is more precise the longer it takes for whatever is being timed. The first roll took 1.8 seconds, the second roll took 2.02 seconds, and the third roll took 1.8 seconds. The spool of thread consistently rolled in a straight pattern and it did not vary often. I also noticed that it did gain speed as it continued to roll. Once I turned the book in 180 degrees, the first roll took about 1.84 seconds, the second roll was 1.56 seconds, and the third roll was 2.04 seconds. When it went the other way, the spool still rolled in a straight line and gained speed along the way.

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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 of the spool of thread down the book was 1.84seconds. The accuracy was kept because I was the one who was clicking the timer button and also the one who let the spool go at the beginning. Because I was able to start and stop the spool at the same points, this made the experiment more accurate.

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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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Since I know that the spool of thread increases in speed as it rolls down the book, I am going to keep that same experiment but add alternate points of when I am going to time it. I will begin by timing, on the TIMER system, how long it takes from the start to the middle, and without stopping the spool, I will see how long it takes to get to the end of the book. I will also add a cm to the height of the printer papers so that it is 3 cm high. Next, I will be taking two time measurements for each roll.

On the first roll,it took .875 sec to reach the middle of the book and .28 seconds to reach the end of the book from the middle.

The second roll took .828 seconds to reach the middle, and .313 to reach the end of the book.

The third roll took .859 seconds to reach the middle and only .313 seconds to reach the end.

Since the average time it takes to reach the middle of the book from the start is .854 seconds, and the average time to reach the end from the middle (from one continuous roll)is .302 seconds, then this supports the idea that the spool of thread increases throughout the experiment. This also supports my data and conclusions.

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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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45 minutes

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

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