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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For the book, I used a 45.7cm X 30.4cm hardcover sketch pad (I couldn't find the ISBN). I propped it up on the edge of a small soft-cover book I am reading called The Doctor's Wife (ISBN 0-452-28691-3). The sketch pad was raised approximately 1.9cm higher on one end than the other, creating a ramp. I used a BIC ballpoint pin as the cylinder. It rolled very smoothly and in a fairly straight line when released. The pin gained speed as it traveled down the sketch pad.

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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 measured the amount of time the pin took(in seconds)(from the moment it was released) to reach the edge of the sketch book. The result from the first 6 trials were as follows:

1. 2.796875

2. 2.96875

3. 3.34375

4. 2.984375

5. 2.828125

6. 3.078125

After I rotated the ramp 180degrees, I also measured the time it took to get from the raised end of the sketch book to the end resting on the table. My results were as follows:

1. 2.078125

2. 2.171875

3. 1.78125

4. 2.515165

5. 1.933125

6. 2.765625

After comparing my 2 sets of results, I found that the second set of data was nearly one second on average faster than the first set. This was likely a result of raising the sketch book higher by mistake when rotating the ramp.

Also, each time I recorded (using the TIMER program) ended with the number 5.

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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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speed = distance / time

To find the average speed, I took the average distance the pin traveled each time (45.7cm) divided by the average amount of time (over all 12 trials) (2.60376 seconds). 45.7cm/2.60376s = 17.55154 cm/second

I realize that my calculation of speed is not completely accurate because there is always a degree of human error. In this case, the second six trials were not under the same conditions as the first. Also, it is impossible to be 100% accurate when measuring time. We have already established that the TIMER program has the ability to measure time accurately to the .01 (or hundredth place).

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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 measured the length of the sketch pad and divided it in half. In the middle of the book (22.9cm from each end), I drew a line across the book. I then measured the amount of time it took for the pin to get to the line (from the moment it was released). My results were as follows:

1. 1.203125

2. 1.3125

3. 1.359375

4. 1.328125

5. 1.375

I then measured the time elapsed from the moment the pin crossed the middle of the book to the edge.

1. .71875

2. .828125

3. .84375

4. .796875

5. .859375

The second set of data is noticeably smaller, indicating the pin is speeding up as it travels down the ramp.

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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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Your work looks very good. Let me know if you have any questions. &#