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PHY201
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.
** Initial Timing Experiment_labelMessages **
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Note: The majority of student report taking less than an hour on this experiment, though a few report significantly longer times.
Take reasonable care to get good data in this experiment. Try to do the timing as accurately as possible. Measurements of length, height, etc. should be reasonably accurate (e.g., with a meter stick or ruler you can measure to withing +- 1 millimeter, but it's not necessary to try to determine fractions of a millimeter).
In this experiment you will use the TIMER program, a hardcover book, the toy car that came in your lab materials package (or, if you do not yet have the package, 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, which is also given on the Assignments page).
• The book's cover should be straight and unbent.
• The toy car (or other 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. For a typical book, a stack of two or three quarters placed under one end works well.
• 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. Once you've got the book set up, it takes only a few seconds to do a timing, so it won't take you long to time the object's motion at least three times.
• Determine how far the object travels as it rolls from its initial position (where you first click the timer) to its final position (where you click at the end of the interval). This will probably be a bit less than the length of the book, due to the length of the object itself.
• Determine how much higher one end of the book was than the other, and how far it is from the supports (e.g., the stack of quarters, or whatever you used to support one end) to the end of the book which rests on the table.
Then reverse the direction of the book on the tabletop, rotating the book an its supports (e.g., the stack of quarters) 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 can of vegetables (full or empty; should be specified) or a jar (again full or empty); anything round and smooth that will upon release roll fairly slowly down the incline), 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?
your brief discussion/description/explanation:
Book used: devotional book that had a hard cover. ISBN 10-0-7369-2211-3
Object: toy car that measured 6cm from one end to the other.
A dice (from the lab package) : ht of 0.7cm
The car rolled smoothly and appeared to go faster as it rolled down. Direction of the car didn’t change while rolling, but when rolling off the book, it changed its direction to the left.
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In the space indicated 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 identify any patterns or trends.
your brief discussion/description/explanation:
measurements included : length of the book, length of the car, height of the dice that the book was raised on at one end, the time taken for the car to roll from rest to reach to the end of the book. Also measured the time taken for the car to move from rest to the 10.5cm mark on the book, and time from 10.5cm to the end of book.
• Book length: 21.5cm
• The height of the incline: 0.7cm
• The length of the car: 6cm
• Total distance traveled = 21.5 -6 = 15.5 cm
• Total time taken measured using the timer = 2.007s = 2s
• Time taken from the car to start from rest and reach the 10.5cm mark = 0.8s. the total distance the car traveled was calculated by subtracting the length of car from the 10.5cm has given me the actual distance the car traveled as 4.5cm and time taken was 0.8 s
• Time taken from the 10.5cm mark to the end of book was 0.34s. the distance traveled here was 21.5-10.5 =11.5cm
event number,clock time,time interval
1 , 2292.258 , 2292.258
2 , 2294.203 , 1.945313
3 , 2305.156 , 10.95313
4 , 2306.535 , 1.378906
5 , 2308.047 , 1.511719
6 , 2309.891 , 1.84375
7 , 2323.551 , 13.66016
8 , 2325.559 , 2.007813
9 , 2368.48 , 42.92188
10 , 2370.371 , 1.890625
11 , 2382.918 , 12.54688
12 , 2384.477 , 1.558594
13 , 2446.313 , 61.83594
14 , 2447.191 , 0.8789063
15 , 2456.453 , 9.261719
16 , 2456.801 , 0.3476563
17 , 2468.609 , 11.80859
18 , 2469.207 , 0.5976563
19 , 2612.77 , 143.5625
20 , 2614.789 , 2.019531
21 , 2646.523 , 31.73438
22 , 2648.281 , 1.757813
23 , 2656.066 , 7.785156
24 , 2658.004 , 1.9375
25 , 2664.297 , 6.292969
I had so many values here, since I repeated the experiment few times before I took the value, and sometimes I wasn’t successful in clicking simultaneously.
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.
your brief discussion/description/explanation:
Average speed Vave can be calculated by dividing the change in distance with the time taken.
Vave = 15.5 cm/2 s= 0.155m/2s = 0.78m/s
When I measured this multiple times, timer gave me values at times 1.9.. to 2.1s. I am guessing the difference of +-0.1s accurate.
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How fast was the object moving at the beginning of the timed interval?
According to your previous calculation, what was its average speed during this interval?
Do you think the object, when it reached the lower end of the book, was moving at a speed greater or less than the average speed you calculated?
your brief discussion/description/explanation:
At the beginning the speed of the object is zero as it is at rest. The car was moving relatively slower as it is starting from zero. The average speed for the whole journey was 0.78m/s
The object was moving at a greater speed at the lower end of the book than the average speed.
When calculated the final speed by using the formula Vave = Vf - V0/2; Vf = 2Vave +V0. The final speed, according to this formula, was 1.56m/s
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List the following in order, from least to greatest. Indicate 'ties': The object's initial speed, its final speed, its average speed, and the change in its speed as it rolled from one end of the book to the other.
your brief discussion/description/explanation:
the car started from rest, so its initial speed Vo = 0. Average speed was calculated from change in distance and time interval -Vave = 0.78m/s. Final speed of the car = 1.56m/s. the change in speed Vf - V0 = 1.56m/s too.
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Devise and conduct 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.
your brief discussion/description/explanation:
I measured another average speed measurement at 10.5cm mark. The car traveled first 4.5cm at an average speed of 0.056m/s. then I calculated the average velocity of the rest of the journey = 11cm and time taken was 0.34s which gave me an average speed of 0.32m/s. almost six times the average speed for the first half of the journey.
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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?
1.5 hour.
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&#Very good data and responses. Let me know if you have questions. &#