initial timing experiment

phy 201

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Initial Timing Experiment

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Here is my initial lab experiment. I did this to the best of my ability and hope it is done correctly.

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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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Materials used: College Physics 3rd Edition by Jerry Wilson and Anthony Buffer, ISBN 0-13-398785-x; Propped up with an artist sketchbook; A spool of pink thread (contained in lab kit); and an Armitron stopwatch for timing.

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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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The spool rolled smoothly and increased in speed as it progressed down the book, traveling in a fairly uniform direction, being nearly a straight line.

Distance = 27cm

Time = 2.26s, 2.42s, 2.01s

Average t = 2.23s

Height = 7mm or .7cm

Reverse Time = 2.13s, 2.11s, 2.14s

Average t = 2.14s

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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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Average Velocity/Speed

First Trial V = Dx = 27.0cm = 12.1cm/s

Dt 2.23s

Reverse Trial V = Dx = 27.0cm = 12.6cm/s

Dt 2.14s

Using the stopwatch for timing, I feel the average speed is fairly accurate, however, upon reversing the ramp(book)I noticed a slight increase in speed. This could have been due to the surface of the book (unseen defects, seams, etc.)

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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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In order to conduct my experiment to determine whether or not the object is speeding up as it rolls down the incline, I had to change my ramp to have a long enough surface to measure a midpoint. New objects consist of poster-framed piece of artwork for ramp, propped up with the same sketchbook and a DVD case. The new data is:

Distance = 58.5cm

Time of first half of ramp = 1.87s, 1.72s, 1.90s

Average t = 1.83s

Height = 3.1 cm

Time from midpoint (second half of ramp) = 2.31s, 2.41s, 2.46s

Average t = 2.39s

Average Velocity/Speed

Initial Time V = Dx = 29.3cm = 16.0cm/s

Dt 1.83s

Midpoint Time V = Dx = 58.5cm = 24.5cm/s

Dt 2.39s

The time the spool traveled down from the midpoint of the ramp was indeed faster than the time the spool traveled down the first half of the ramp, therefore the object is speeding up as it rolls down the incline.

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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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Approximately 2 hours

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

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Hope you have a great weekend! Please let me know if this my work is incorrect.

Your work looks good. Hope your weekend is a good one.