initial timing experiment

Phy 231

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 the physics book required for this class with a domino placed under the one end of the book to raise it up. I used a small sized can of corn as the object to roll down the book. The object rolled down in a little less than two seconds the way the book was set up the first time. However when I switched the book around 180 degrees it took three seconds to make it to the end which means my counter is not exactly level. The object however rolled fairly straight and speeded up slightly once it got near the end, but not a real big difference.

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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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I measured the length of the book how high the domino raised the book at one end and also I recorded the three different time trials. The times were measured using the timer program and the measurements were made using the ruler printout that was given in the take home lab kit. I believe that the measurements were fairly accurate possibly plus or minus a millimeter on the total book length and height of the domino.

Book before it was rotated 180 degrees

Three time trials: 1.844, 1.828, 1.734

Length of the book: 39.7cm

Height the book was raised at one end: 1.35cm

Book after it was rotated 180 degrees

Three time trials: 3.047, 2.844, 3.000

Length of the book: 39.7cm

Height the book was raised at one end: 1.35cm

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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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By taking the average of the three different time trials for both ways I came up with an average time in second. I took the length of the book and divided that number by the two different average times to come up with my speed for both trials.

Book before it was rotated 180

Speed=22.03cm/s

Book after it was rotated

Speed=13.4cm/s

Average speed = 17.2cm/s

Based on my data I do believe that my calculations were accurate, but due to the counter being slightly un-level this data is not the best. This is the only counter I really have to do this on unless I did it on the floor, but I believe I might experience the same kind of issue

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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 would conduct an experiment by timing it takes the can to make it half way down the book and then record how long it takes to make from half way to the end of the book. This would tell me whether or not the can is actually speeding up as it goes further down the incline. By doing so the can is speeding up and it takes less time in seconds to reach the end then it does the halfway point

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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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about 45 minutes

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

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As you will see in my data my counter is slighlty not level which when i rotated the book it caused the can to take longer to reach the bottom

Very well done.