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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For this experiment I used the assigned book for this class. This book is ‘Physics’ by Giancoli, 6th edition. I also used a full can of green beans and one domino piece. I began by laying the book perpendicular against a wall. Next I put the domino piece under the end of the book opposite of the wall. I then used the timer program to measure the time it took for the can of green beans to roll from its initial position to its final position. The can of green beans rolled in a fairly straight line. The can also hesitated a few times in the middle of the book before it continued to roll to its final position. The total distance the can traveled was approximately 0.228 m. I performed three trials and my results are as follows:

Trial 1: 3.69 sec

2: 3.34 sec

3: 3.53 sec

Next I rotated the book 180 degrees in the exact opposite direction with the same procedure as earlier stated and again performed three trials.

Trial 1: 3.79 sec

2: 4.01 sec

3: 3.86

The can tended to hesitate even more in the middle of the book this time than last time. I could have propped the book up with 2 dominos but the can would have rolled from the initial position to the final position in less than 2 seconds.

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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 this experiment the length of the book with measured (0.228 m), the length the book was propped up from the floor to form a slope (0.127 m from the floor), and amount of time (in seconds) was measured for the can of beans to roll from its initial position to its final position. The time measurements were fairly accurate but not completely accurate. The can tended to stall in the middle of the slope was occasionally my assistance was needed to help the can of beans to continue rolling down the slope. Because of this, I could have affected the time for the can of beans to roll from one position to the other because my assistance was not consistent. The results are as follows:

Set 1:

Trial 1: 3.69 sec

2: 3.34 sec

3: 3.53 sec

Set 2:

Trial 1: 3.79 sec

2: 4.01 sec

3: 3.86 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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The average speed for first set of trials was 0.06477 m/s. The average speed for the second set of trials was 0.05866 m/s. The overall average speed was 0.06157 m/s. I don't think my results were very accurate because at times I had to give the can an extra boost to roll down the slope. Therefore, my assistance was not consistent with each trial; thus, the results were affected.

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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 my experiment I used the same can of beans and I used a three ring binder for my slope. The can travelled at rate of 0.3048 m/s. The average time for the can to roll from its initial position to its final position was found to be approximately 3 seconds. Therfore, the can travelled a distance of 0.1016 m/s. By dividing up the velocity on different points of the slope it is obvious to see that the can of beans speeds up at it rolls toward it final position. Through calculation it was found that on the first half of the slope the can rolled 0.06773 m in 1.5 seconds. On the second half of the slope the can rolled 0.03387 m in 1.5 seconds. Therefore, the can speeds up as it rolls down the slope.

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