initial timing experiment

Phy 201

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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used the Physics Giancoli Sixth Edition textbook that is required for class. Along with that, I used a spray bottle with a height of about 20.5 cm and a width of 1.75 cm. It is completely full with lavender oil. In order to prop the textbook, I used a typical pen with the cap removed. It has a height of 14.5 cm and a width of .75 cm. The spray bottle rolled down straight and smooth. It increased speed as it went down.

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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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Times for spray bottle to travel 28cm across book - 1.734375, 1.78125, 1.765624.

Times for spray bottle to travel 28cm in reverse direction – 2.34375, 1.984375, 2.03125

I measured the time using the TIMER program and began once my hand left the spray bottle and stopped when it clearly left the book and landed on the table.

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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 spray bottle was moving on average a speed of 25 cm per 1.9401 seconds. I believe my average is fairly accurate but it is very difficult to keep all the variables involved in the experiment constant; for example, clicking the timer at the same time as releasing could vary as well as some minor force applied to the object when releasing. Therefore, I believe my average is as accurate as it may get.

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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 used the same design as before, including the physics textbook, spray bottle, and pen. I marked off half the distance of the book at 14cm. I timed how fast the spray bottle reached 14cm and how fast it reached the second 14cm. I found that on average the spray bottle went the first 14 cm in 1.67969 seconds to give the average speed of 14 cm/1.67969 seconds and for the second 14cm it took the spray bottle .523438 seconds. Therefore, it showed the spray bottle increased speed over time.

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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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&#Good responses. Let me know if you have questions. &#