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Phy 121
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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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: Physics Principles with Applications (ISBN: 13:978-0-321-625922)
Object used: Marble
Object used to prop book: 2 quarters
I proped the top of the book up using the 2 quarters, placed the ruler along the left side of the book and held the marble at rest at the top of the book before releasing it.
The marble rolled real well down the book and rolled in a some what straight line down the book picking up speed as it rolled.
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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:
Book Length: 11 inches
End of Book on Table: 1.52 inches
Proped up end of Book: 1.77 inches
2 quarters: 0.25 inches
Difference in Book end heights is 0.25 inches
I ran the three times and I recorded them down according to 3 different marks on the ruler:
Test 1 (5 inches): 1.40
Test 2 (8 inches): 1.91
Test 3 (11 inches): 2.34
180 degree rotation:
Test 1 (5 inches): 1.70
Test 2 (8 inches): 2.12
Test 3 (11 inches): 2.53
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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.
your brief discussion/description/explanation:
The marble was measured at inches per second going down the incline.
I feel that my measurements are accurate because I hit the time at the predetermined measurements.
Test 1 (5 inches): Initial velocity: 0, Average velocity: 3.57 inches/second, Final velocity: 7.14 inches/second
Test 2 (8 inches): Initial velocity: 0, Average velocity: 4.19 inches/second, Final velocity: 8.38 inches/second
Test 3 (11 inches): Initial velocity: 0, Average velocity: 4.70 inches/second, Final velocity: 9.40 inches/second
180 degree rotation:
Test 1 (5 inches): Initial velocity: 0, Average velocity: 2.94 inches/second, Final velocity: 5.88 inches/second
Test 2 (8 inches): Initial velocity: 0, Average velocity: 3.77 inches/second, Final velocity: 7.54 inches/second
Test 3 (11 inches): Initial velocity: 0, Average velocity: 4.35 inches/second, Final velocity: 8.70 inches/second
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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:
The marble was moving at 0 starting because it had not been released to start rolling.
The average speed during this interval is 4.15 inches/second and for 180 degree rotation is 3.69 inches/second.
When the marble reached the end of the book it was moving at a speed greater than the average speed.
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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:
Test 1: Initial speed: 0, Average speed: 2.18 in/s, Final speed: 4.36 in/sec
Test 2: Initial speed: 0, Average speed: 7.80 in/s, Final speed: 15.6 in/sec
Test 3: Initial speed: 0, Average speed: 19.82 in/s, Final speed: 39.64 in/sec
Rotated the book 180 degrees:
Test 1: Initial speed: 0, Average speed: 2.61 in/s, Final speed: 5.22 in/sec
Test 2: Initial speed: 0, Average speed: 7.80 in/s, Final speed: 15.60 in/sec
Test 3: Initial speed: 0, Average speed: 17.60 in/s, Final speed: 35.20 in/sec
The marble is picking up speed as it goes down the incline at a decreasing at a increasing rate.
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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 don't know of any other experiment to determine whether the marble is speeding up as it rolls down the incline unless you can attach some kind of speedometer to it.
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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 hour
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Nice work, well done.
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