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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).

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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Giancoli 6th edition, ISBN 0-13-060620-0

full can of sloppy joe

the book was propped up on 2 stacked dominoes. the can appeared to roll in a straight line with a speed that was constant until the end of the run where it sped up

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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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test 1 - book raised on one end 4.5 cm, length of run is 28 cm

each run was measured in cm measuring from one edge of the book to the opposite edge running longways

run 1 : 2.2 seconds

run 2 : 2.3 seconds

run 3 : 2.5 seconds

test 2 - book raised on one end 4.5 cm, length of run is 28 cm, book was turned 180 degrees from test 1

run 1 : 1.1 seconds

run 2 : 1.1 seconds

run 3 : 1.2 seconds

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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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avg speed = d / t

test 1 yielded an average speed of 12.2 cm/s

test 2 yielded an average speed of 24.8 cm/s

I'm unsure why the two tests have a dramatic difference in results. I repeated the experiment several times, giving me the same results for each test. It might be that the book had some irregularities on the cover or it could have been the gravitational pull of the moon on the Earth's surface. Go figure?

the formula for average speed is pretty straight forward. Just plug in the numbers in the right places and depending on whether or not the data is reasonable will determine how believable the end result will be

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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 set my experiment up by elevating the book on top of two stacked dominoes and placed a mark in the center of the book on the long edge. I then started the can rolling, starting the timer at the same time. When the can reached the halfway point I timed the can and then timed it again when it reached the end of the run.

time between initial release and halfway point : .58 seconds

time between halfway point and end of the run : .45 seconds

As you can see, it took the can a little over half a second to go half way and less than half a second to finish the run

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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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Excellent work.