initial timing experiment

phy 121

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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I used our physics book “Giancoli” as the base for the ball, I used a ping pong ball for the rolling object. To prop the book up I used a note book along with a couple sheets of paper. To prop the ball up I used a rolled up posted note that I could pull away from the ball pretty easily. When conducting the experiment the ball rolled very smoothly and rolled just a little bit to the left.

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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 raised end of the book was 4.75cm high while the other side was 3cm high. The distance that the ball traveled was 27 and ½ centimeters. The ball took 2.35, 2.4, and 2.43 seconds to fall off the other on of the book. After this I turned the book around 180 degrees and repeated the step. The book was still 5cm on the high side and 3cm high on the low side. This time I recorded 2.39, 2.42, and 2.34 seconds, I think that both of the trials took about the same time to travel from one end of the book to the other.

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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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I believe that the ball was rolling at 11.7 cm/s. I believe that this is a pretty close estimate but might be a little off because of human error.

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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 tried to put a pencil right in the middle of the book at about 13.75 cm down the book. then i let the ball roll and got the time of it. Then i let it roll down the rest of the book and looked at the time, i noticed that it was at a much slower time, showing that the ball speeds up as it makes it way down the book.

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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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35 to 45 minutes

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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. &#