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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I used the Physics book from this class (ISBN 0-13-060620-0). I propped the edge with 2 stacks of quarters with 5 in each stack. The can was a 15 oz can of seasoned cabbage. The can rolled smoothly, somewhat slowly, and fairly straight.

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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 used the timer program to time the can roll for a total distance of 22cm. I had to use the printed metric scale. The timed measurements were somewhat consistent but I the old trial of counting by thousands for time indicated the timer program was running fast or I was counting slow.

1st. 1.93, 1.89, 1.84, 1.75

reversed book 2.15, 2.19, 1.88, 1.73

The trend looked like the more it rolled, the faster the can travel across the distance. I guess I was tracking the groove on the book.

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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 can rolled at an average of 1.92s over the distance of 22cm. I suppose the speed would be determined as 11.46 cm/sec. I really don't feel the accuracy was at a premium because of clicking the timer versus timing eyes and the home made scale I used.

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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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You would have to time the can roll at several distances. Since I used 22cm of total distance, 4 timing spots at 5.5cm intervals and some really fast clicking on the timer program would probably yield and acceleration curve.

The timer intervals supported my conclusions.

1st. .89

2nd. .38

3rd. .29

4th. .19

At some point in time the acceleration will even out to a consistent time lapse

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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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This experiment took me approximately 45 minutes because I had a lack of confidence in the timer figures.

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

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It took me a few minutes to find where I saved the timer program.

Nice work on this experiment.