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 Sixth Edition Physics by Giancoli the ISBN is 0-13-060620-0. I used a small steel ball bearing with a diameter of about 12mm. I used a BIC fine tip ball point pin to prop the book up. The ball rolled pretty smoothly in a straight line and sped up the farther it traveled

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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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In both sets of timings the book was 284mm long and elevated 9mm.

For the first direction my data was:

1)1.988281 sec.

2)1.96875 sec.

3) 2.078125 sec.

4) 2

5)1.921875

The distance the ball traveled was 305mm

The second direction data was:

1)1.375 sec

2)1.453125 sec

3)1.5 sec

4)1.5 sec

5)1.519531 sec

The distance the ball traveled was 291mm

The length measurments should be within a millimeter or 2 and the times are probably going to be of by a few thousands.

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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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For the first direction I added up all 5 times then divided by 5 to get an average time of 1.9914062 seconds. I then divided that by the distance it traveled 305mm to get an average speed of 153.16mm/sec. I did the same for the second set of times to get an average speed of 198.02mm/sec. Then I averaged these two speeds to get an overall average of 175.59mm/sec. The accuracy of my estimate is probably within a few mm/sec you have to take into account the human error when starting and stopping the timer

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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 distance the ball was traveling to be 287mm and marked a spot half of that distance(143mm) and measured the time it took to travel the first and second halves.

This is my data:

First half:

1)1.285 sec

2)1.523 sec

3)1.105 sec

4)1.125 sec

5)1.203 sec

Second half:

1).6367

2).65625

3).546875

4).546875

5).6132813

The average time for the first half of the run was 1.2482 sec divide 143mm(distance traveled) by this and the average speed for the first half of the run was 114.56mm/sec.

The average time for the second half of the run was .6 seconds so the average speed for the second half of the run would be 240mm/sec. This is more than twice the average speed of the first half of the run proving that the ball speeds up.

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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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30-40 minutes

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

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