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course Phys201
6/20@6:57pm
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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:
In doing my experiment, I used the Giancoli Physics text 6th edition (ISBN:013035256X) propped up horizontally for my ramp. I used a roll of red thread as my moving object. This was the roll that came in the introductory lab package. The roll has a cylinder shape. I used my iphone 4s to prop up the book on its longer end. The iphone served as a .7in supporter. The higher end of the book was 2.1 in. The lower end was 1.5 in in height. The length of the ramp is 8.5 inches. When the cylinder starts rolling down the ramp initially it is slower and as it got to the lower end, it began to speed up.
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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:
The iphone served as a .7in supporter. The higher end of the book was 2.1 in. The lower end was 1.5 in in height. The ramp itself was 8.5 inches in length. Measurements for the supporter were taken from the tabletop to the end of the far end of the iphone. Meausrements for the higher end of the book were taken from the tabletop to the far end of the book. Measurements for the lower end were taken from the tabletop to the far end of the book. The ramp length was measured horizontally across the book.
The amount of time it took for the cylinder to reach the bottom of the ramp from the top of the ramp was measured using the Timer system.
Trial 1:1.21875 sec
Trial 2:1.199219 sec
Trial 3:1.488281 sec
After reversing the book 180 degrees your times were:
Trial 4:1.222656 sec
Trial 5:1.441406 sec
Trial 6:1.269531 sec
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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:
To find how fast the object was moving, on the average as it rolled down the incline add the three times=1.21875sec+1.199219sec+1.488281sec=3.90625 sec then divide by 3 to get an average. Your final average is 1.30208333 sec. You can then take an average of when you rotated the book by adding those three times: 1.222656 sec+1.441406 sec+1.269531 sec=3.933593 sec then divide by 3 to get an average of 1.311197667 sec. You could also combine both sets of data to get a better estimate if you wanted by adding all of the times: 1.21875sec+1.199219sec+1.488281sec+1.222656 sec+1.441406 sec+1.269531 sec=7.839843 sec. You would then divide this by 6 getting 1.3066405 sec.
I think the average gives us a general idea but is not 100% accurate because you cannot control when and how so I could click the mouse to time. So I think that there could be some room for error there. I also tried to regulate where and how I dropped the cylinder at the top of the ramp but I know that each trial was not an exact replicate. Overall, I think there could be some inconsistencies.
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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 object was moving slowly at the beginning of the timed interval. The average speed was 1.30 sec. I think when the object reached the lower end of the book it was moving at a faster speed.
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1.30 second is not a speed, it's a time interval.
It isn't clear which of the requested velocities this time interval is related to, or how it is related.
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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:
Initial times for all trials will all be 0 in/sec.
Final speed:
5.71 in/sec (trial 3)
5.90 in/sec (trial 5)
6.70 in/sec (trial 6)
6.97 in/sec (trial 1)
6.95 in/sec (trial 4)
7.08 in/sec (trial 2)
Average speed:
2.86 in/sec(trial 3)
2.95 in/sec(trial 5)
3.35 in/sec (trial 6)
3.48 in/sec (trial 4)
3.49 in/sec (trial 1)
3.54 in/sec (trial 2)
Changes in speed:
5.71 in/sec (trial 3)
5.90 in/sec (trial 5)
6.70 in/sec (trial 6)
6.95 in/sec (trial 4)
6.97 in/sec (trial 1)
7.08 in/sec (trial 2)
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How did you determine the initial speed of the object as it rolled from one end of the book to the other?
How fast was it moving when it was released at the top of the book?
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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 constructed an experiment to determine whether or not an object speeds up as it rolls down an incline. In my experiment, I used a 33.7 in white board propped up by 3 physics books (Giancoli Physics, University Physicsc 2nd edition by Richard Wolfson vols. 1 and 2). All three books on top of each other are 2.5 in in height. The board itself is 2.5 in in height. Therefore, the total incline is 5 inches. I used a toy car and rolled it down the 33.7 in white board. I marked the white board at the half way mark at 16.85 inches. I used the TIMER program, clicking the mouse when the car was released, when it hit the half way mark, and when it reached the end. In doing this, the three timed points (beginning, middle, and end) will give you 2 velocities and the 2 velocities will give you acceleration. If you look at my results charted below, the speed in column 1 is the initial speed. The speed in column 2 represents where the car was at the ½ point. The speed in column 3 is the final speed.
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Very good description of your setup and methodology.
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Initial Speed (1) ½ point (2) Final Speed (3)
0 13.06 31.20
0 15.46 24.78
0 14.53 27.18
0 17.37 22.17
0 15.32 28.56
0 12.04 33.04
**** All of these values would have units of in/sec******
Furthermore, you can see in the chart below I calculated change in velocity by subtracting the velocity at the ½ point minus the initial velocity. In the second column, I subtracted the final velocity from the velocity at the ½ point.
velocity at the half-v0 vf-velocity at the half
13.06 18.14
15.46 9.32
14.56 12.65
17.37 4.8
16.32 13.24
12.04 21.0
**** All of these values would have units of in/sec******
In conclusion, one can determine from this experiment that change in velocity increases acceleration. The object is definitely speeding up as it rolls down the incline.
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What you've done here looks promising, but you haven't included your data (the TIMER results) so it's not possible to tell if you have analyzed your data correctly.
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In any analysis you need to provide your raw data (what was actually observed), sample calculations showing how you analyzed your data, and your conclusions.
You've got the conclusions, but you're missing the data and sample calculations.
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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?
6hours
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Good descriptions, and the data you have provided look very good, as does much of your analysis.
However a little more is still required.
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I've inserted three notes, each of which indicates the need for either clarification or modification.
&#Please see my notes and submit a copy of this document with revisions, comments and/or questions, and mark your insertions with &&&& (please mark each insertion at the beginning and at the end).
Be sure to include the entire document, including my notes. &#
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