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 used the Sixth Edition Physics, by Giancoli textbook,

ISBN 0-13-060620-0. I used the roll of thread that i received in my intial lab kit as the rolling device. It was probably only half full of thread and 1 inch in legnth and a 1/2 an inch in diameter. I used 1 domino from the lab kit as the prop to incline my book. The object did not roll so smoothly, but it did increase in speed down the book. The roll of thread rolled pretty much in a straight line down the incline.

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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 determined that the length of travel for the roll of thread was 11.1 inches (the lenght of the book). The height of the propped up end of the book was 1.8 inches and the lower end was 1.5 inches, a difference of .3 inches. I used the timer program to time the roll of thread as it travel from the high end of the book to the low end. The results in seconds by the timer program where as follows:

2.53125

2.304688

2.507813

Then I put the domino on the other end of the book and tested the experiment with the roll of thread going 180 degrees opposite. Here was the results:

2.234375

2.179688

2.109375

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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 time the ball of thread took to roll down the incline of the book was 2.3112 seconds. I would say the speed of the ball of thread was 4.8 in/s, by using the formula average speed= distance traveled (11.1 inches)/time elapsed(2.3112 seconds). I believe you can only be but so accurate because of the timer program and exactly the moment when the roll of thread starts and stops in not exactly certain.

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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 decided to break the book up into quarters and timed the ball of thread as it moved past each quarter mark. I then noticed the time intervals between each quarter and checked to see which one was shorter or longer in time. The last quarter near the bottom of the book was the shortest time interval, therefore the ball of thread is indeed speeeding up as it goes down the incline. Actually, the first quarter was the longest, then the 2nd, the 3rd, and the fourth beign the shortest amount of time (the fastest).

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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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1 hour

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

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Good work. Let me know if you have questions. &#