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 my kitchen table as my flat surface. The book I used was the Sixth Edition Physics book by Giancoli ISBN 9780321569837. I propped my book up slightly with a Princess School number 2 pencil. My object that rolled was a can of Giorgio sliced whole mushrooms. The object rolled smoothly and in a straight line. It rolls fairly slowly down the incline and sped up as it went. The can was 6.8cm tall with a diameter of 6.5 cm.
length of book: 28.8cm
diameter of can: 6.5 cm
height of can: 6.8 cm
weight of can: 4 oz
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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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First direction:
Trial one: 3.945313
Trial two: 3.488281
Trial three: 3.816406
Length of book 28.8cm
Can actually traveled 32.1cm
Difference in height 1.3 cm
Second Direction:
4.433594
4.589844
4.6875
Actually traveled 32.1cm
Length of book: 28.8cm
Height difference: 0.1 cm
The time it took to roll down the book was measured by the timer program. The length of the book was measured using a ruler, as well as the length that the can actually traveled. To find the difference in height, I measured the height at the side I released the can and subtracted the height of the end where the can finished rolling.
For the first direction, this was 4.3 cm- 3.0cm= 1.3 cm, and for the second direction, 4.1 cm-3.0cm= 1.1 cm.
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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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Speed is found by taking distance divided by time. It is the change in distance over the change in time. For the first direction you would find the speed for each trial and then find the mean.
trial 1: 5.6 cm/sec
trial 2: 6.3 cm/sec
trial 3: 5.8 cm/sec
The average of these speeds is: 5.9 cm/sec
Second Direction:
Trial one: 5.0 cm/sec
Trial two: 4.8 cm/sec
Trial three: 4.7 cm/sec
The average of these speeds is: 4.8 cm/sec
The average of both trials is (4.8+5.9)/2= 5.35 cm/sec
I feel that I could determine the speed with some accuracy, but there were some variables in the experiment that may have confused results such as where the pencil was placed under the book. This placement could cause varying heights. Also the timer is only accurate to the .01 seconds. Finally, human error could have hurt the accuracy. My clicking of the timer could have been off slightly. Overall the experiment seems like good practice for somewhat accurately determining average speed.
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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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You could record the time intervals of different segments of the book. In my experiment, I will simply cut the book into two intervals. I will start the timer on release, click the timer when the can reaches halfway down the book and record that interval. I will then do the same for when the can reaches the end of the book. If the can is in fact speeding up, the time it takes to reach the middle will be longer then the time it takes to reach the end from the middle. I will use the same apparatus as used in the above experiment using the same book, can, and prop. Each interval will be 13 cm and the can will travel a total distance of 26 cm.
DATA:
0-13cm:
trial 1: 1.898438 sec
speed= 6.8cm/sec
trial 2: 1.816406 sec
speed= 7.2cm/sec
trial 3: 1.839844 sec
speed= 7.2cm/sec
average speed for 0-13= 7.1 cm/sec
13-26cm:
trial 1: .8359375 sec
speed= 15.5cm/sec
trial 2: .703125 sec
speed= 18.6cm/sec
trial 3: .84375 sec
speed= 15.5 cm/sec
average speed 13-26cm: 16.5cm/sec
Based on my data the average speed of the second interval is faster than the average speed of the first interval, this indicates that the can is in fact 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:
- Approximately how long did it take you to complete this experiment?
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40 minutes
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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. &#