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.
** template formInitial 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).
- 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 6th edition Physics Giancoli book ll inches long and 1.27inches thick propped upon a solid black bangle braclet,1 inch thick. I used a full can of tomato as my rolling object. The object rolled smoothly and in a straight line each time. The total rolling time only took about 1 second and it appears the can speeds up as it rolls 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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Time I Rolling can measurements (in seconds)
1 120.8906 120.8906
2 121.1875 .296875
3 121.6094 .421875
4 121.8281 .21875
Total time= .9375 seconds
Time 2
5 173.5938 51.76563
6 173.8594 .265625
7 174.1719 .3125
8 174.4531 .28125
Total time= .8593
I did two trials of the experiment and found the total rolling time was less than one second from the time of release to the time the can fell off the book. Between the two trials was a .0782 second difference. I do believe there could have been a less difference but the experiment if my incline had been longer and therefore would have been more accurate. I believe my data was close to the actual time.
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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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to determine the speed of an object i will use the velocity equation
change in x/change in t
Time I
x/t = 11in/.9375seconds
= 11.7333 inch/sec.
Time II
x/t = 11in/.8593seconds
= 12.8011 inch/sec.
I think when changing the incline 180 degrees it was increased because the second time trial showed the can rolled the same distance but in faster amount of time.
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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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Increased Time I Difference in time vs. position
1 1020.359 1020.359 position I to II = .688
2 1021.047 .6875
3 1021.438 .390625 position II to III = .391
Increased Time II
4 1044.703 23.26563 position I to II = .675
5 1045.375 .671875
6 1045.672 .296875 position II to III = .302
Again I recorded two times to verify my conclusion that the can sped up as it rolled down the incline. I measured 3 times and positions for this experiment. The first time was taken as the can started to roll down the incline. Second time was recorded as the can passed the middle of the book, and the third time was recorded as the can rolled off the book. By calculating the time from position one to two and then two to three you can see the can moves almost 2x as fast further 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:
- Approximately how long did it take you to complete this experiment?
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45 minutes
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You may add optional comments and/or questions in the box below.
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Your work here is well done.