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initial timing experiment

Phy 121

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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Wednesday August 5 - quarter to 11

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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).

The book's cover should be straight and unbent.

The object should roll fairly smoothly.
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.

Using the TIMER program determine how long it takes the ball to roll from one end of the ramp to the other, when released from rest. Time the object's motion at least five times.

Determine how far the object actually travels as it rolls from one end to the other.

Determine how much higher one end of the book was than the other, and how far it is from one end to the other.
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 Hardcover Physics Book (Biographical Dictionary of Scientists: Physics by David Abbott, Phd.) and a small, 3in tall and 2.625in diameter, full tin of green beans to conduct this experiment. To prop up my book I used a domino, one at each side of the book, which raised it about 8mm more off the ground. During the experiment, the tin of beans rolled smoothly down the hill in one direction and seemed to speed up as it went down the incline.

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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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Length of Incline - Measured with cm ruler down middle - 20.5cm

Length of raised end - Domino (8mm) added to book depth (2.3cm) - 3.1cm

Length of lowered end - Book Depth - 2.3cm

Average of Roll 1 - 6 rolls down incline - 1.9 seconds

Average of Roll 2 - 6 rolls down incline - 1.8 seconds

All timed measurements are accurate to within .1 second

All other measurements are accurate to within 1mm

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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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After calculation - the average speed is 11.1cm per second. This is the result of the total length traveled (20.5cm) divided by the total average (1.85 seconds).I believe this is accurate to within 1mm. I say this because the total average is a combination of 2 averages.

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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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Using the same variables I placed a second ruler exactly halfway down the incline to stop the can of peas. After a series of 4 runs I found that on all the runs it took 1.2 seconds to get from the starting place to the midpoint meaning it must complete the remaining half in less than .7 seconds, concluding that the can is speeding 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:

Approximately how long did it take you to complete this experiment?

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.

** template form

Initial Timing Experiment

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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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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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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. &#