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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The book I used was my JR Tucker High School Yearbook. It's 305 pages and about 1.5lbs. My cylinder was a crayola magic marker. I propped hte book up with a 1 subject notebook. The object rolled smoothly all the way down, however the direction changed a little toward the end of the roll.

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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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Measurements:

Taken with a centimeter ruler. Measurements are accurate to one tenth of a centimeter. Time measurements taken with the timer program.

Book Length: 31 cm

Incline: .05 cm

Time for Marker to Roll When Book Propped from Left side

2.363281 sec.

2.203125 sec.

2.160156 sec

2.382813 sec.

2.485375 sec.

Time for Marker to Roll When Book Propped from Right Side

2.382813 sec.

2.203125 sec.

2.324219 sec.

2.433594 sec.

2.363281 sec.

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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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From the book propped from the left side, the average speed was 13.36 cm/sec. From the book propped from the right, the average speed was 13.24 cm/sec. I think my estimates are as accurate as a person can get when measuring by hand. It's hard to be 100% accurate when you are just pushing a mouse pad to get the timing results 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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For this experiment, I got measurements from the first ten centimeters of the roll and the last ten centimeters of the roll.

Measurements:

1st Ten cm.

1.089 sec.

.8789 sec.

.921875 sec.

.9804 sec

.86382 sec.

Last Ten cm.

.4592 sec.

.46031 sec.

.5195 sec.

.47265 sec.

.46875 sec.

Average Speed for First 10 cm. = 10.56 cm/sec.

Average Speed for Last 10 cm. = 20.24 cm/sec.

The average speed is much faster for the last ten seconds proving that the marker did speed up throughout it's trip 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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40 minutes.

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

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Excellent report.