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 a Middle School annual as my book with 4 CD’s in plastic cases to prop it up. The book is flat and not very thick. I used a full can of Dr. Pepper as my cylinder.

The book is approximately 27.5 cm long and the height of the CD's were approximately 8 mm high.

The can rolled very smoothly and straight. It started slow and gained speed.

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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 first set of rolls (toward the right) were as follows:

1.890625 seconds

1.84375 seconds

1.90625 seconds

1.921875 seconds

The second set of rolls (toward the left) were as follows:

1.25 seconds

1.21875 seconds

1.296875 seconds

1.203125 seconds

I put a pen on the starting side of the roll and a remote control at the end. I tried to be as accurate as possible but with these devices, I don’t think they can be too accurate. Maybe +/- .1 of a second.

I conducted the experiment on my computer desk and it looks as if the computer desk is not flat because rolling it to the left is much faster than rolling the can to the right.

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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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Rolling the can toward the right, it rolled an average of 1.890625 seconds/27.5 cm.

Rolling the can toward the left, it rolled an average of 1.2421875 seconds/27.5 cm.

The average speed accuracy depends on the individual time measurements. If all the measurements and factors of the experiments were done perfectly, the times on every roll should be the same. Because of the flaws in the measurements as stated above, we can only measure the average of the measurements we obtained. To determine the average speed, I added the 4 speeds and divided by 4.

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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 put a piece of tape directly in the middle of the book and timed the point the can rolled over the tape and again when it reached the end of the book.

My data is a follows: the first figure is from the beginning to the midway point and the second figure is from midway to the end.

1.359375 - .596875

1.390625 - .609375

1.328125 - .6875

1.40625 - .671875

This data supports that the can picks up speed as it rolls. It takes longer to roll down the first half of the book than it does the last half. My data shows that it rolls over twice as fast from the halfway point to the end than it does from the beginning to the middle.

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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 min.

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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. &#