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phy201
Your 'ball down ramp' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** Ball Down Ramp_labelMessages **
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A ball is timed as it rolls from rest to the end of a ramp. The slope of the ramp is varied. Preliminary conclusions are drawn about the motion and the effect of ramp slope. A subsequent lab exercise uses the data from this lab to reach additional conclusions.
Most students report completion times between 45 minutes and 75 minutes hour, with a few reporting times as short as 25 minutes or as long as 2 hours. Median time of completion is around 1 hour.
Timing Ball down Ramp
The picture below shows a ball near the end of a grooved steel track (this steel track is a piece of 'shelf standard'); the shelf standard is supported by a stack of two dominoes. Your lab materials package contains two pieces of shelf standard; the shelf standard shown in the figure is white, but the one in your kit might be colored black, gold, silver or any of a variety of other colors.
If a ball rolls from an initial state of rest down three ramps with different slopes, the same distance along the ramp each time, do you think the time required to roll the length of the ramp will be greatest or least for the steepest ramp, or will the interval on the steepest ramp be neither the greatest nor the least? Explain why you think you have correctly predicted the behavior of the system.
Your answer (start in the next line):
I think that the time will be least for the ball to roll down the steepest ramp because with a steeper ramp the ball will be able to accelerate at a faster rate making the ball hot the end sooner.
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If we write down the slopes from least to greatest, next to the time intervals observed for those slopes, would you expect the time intervals to be increasing or decreasing, or do you think there would be no clear pattern? Explain why you think you have correctly described the behavior of the numbers in the table.
Your answer (start in the next line):
I think that the time intervals will be decreasing. So if the slope is the least steep it will take the longest for the ball to roll down the ramp and when the ramp is the steepest is will take the shortest time. Again, I think that the ball will be able to reach its peak acceleration at a faster rate with the steepest ramp making the ball reach the end of the ramp the fastest.
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Set up the shelf standard ramp on a reasonably level table, using a piece of 30-cm shelf standard and a single domino under the high end of the ramp. Position the dominoes so that the last .5 cm of the ramp extends beyond the point where the ramp contacts the domino,.and do the same in all subsequent setups.
Set the bracket on the table, touching the lower end of the ramp so that a ball rolling down the ramp will strike the bracket..
Mark a point about 3 cm below the top end of the ramp. Place a domino on the ramp to its high end is at this point, and place the ball just above the domino, so the domino is holding it back. Quickly pull the domino away from the ball so the ball begins to roll freely down the ramp. Allow the ball to roll until it strikes the bracket.
The bracket will probably move a little bit. Reset it at the end of the ramp.
Determine how far the ball rolled from release until it struck the bracket.
Now repeat, but this time use the TIMER. The first click will occur at the instant you release the ball, the second at the instant the ball strikes the bracket. Practice until you are as sure as you can be that you are clicking and pulling back the domino at the same instant, and that your second click is simultaneous with the ball striking the bracket.
When you are ready, do 5 trials 'for real' and record your time intervals.
Then reverse the system--without otherwise changing the position of the ramp, place the domino under the left end and position the bracket at the right end.
Time 5 trials with the ramp in this position.
In the space below, give the time interval for each trial, rounded to the nearest .001 second. Give 1 trial on each line, so that you will have a total of 10 lines, the first 5 lines for the first system, then 5 lines for the second system.
Beginning in 11th line give a short narrative description of what your data means and how it was collected.
Also describe what you were thinking, relevant to physics and the experiment, during the process of setting up the system and performing the trials.
Your answer (start in the next line):
2.33
2.18
2.78
1.82
1.87
1.88
2.31
1.95
1.87
1.94
The data above was collected using the timer program on the computer while timing a ramp constructed from the instructions in the above directions. My data represents that the ball took approximately 1.82 seconds to 2.78 seconds to roll down the constructed ramp. Looking at the data with the numbers at the beginning you can see that the left side had faster times than the right side ramp. During this short ramp experiment my mind was sticking with my hypothesis that the shortest ramp would yield the largest numbers making the ball take longer to get to the bottom of the ramp.
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Now place two dominoes under the right end and repeat the process, obtaining the time interval for each of 5 trials.
Then place the two dominoes under the left end and repeat once more.
Enter your 10 time intervals using the same format as before.
Your answer (start in the next line):
1.51
1.46
1.58
1.75
1.52
1.09
1.18
1.19
1.03
1.17
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Repeat the preceding using 3 dominoes instead of 2. Enter your 10 time intervals using the same format as before.
Your answer (start in the next line):
1.03
1.01
1.07
1.02
1.09
.928
.893
.901
.868
.903
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Repeat the preceding again, still using the 3 domino setup, but this time place a CD or a DVD disk (or something of roughly similar thickness) on the 'low' end of the ramp. You need time only 5 intervals, but if you prefer you may use 10. Enter your 5 (or 10) time intervals using the same format as before.
Your answer (start in the next line):
.874
.903
.908
.889
.893
.
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Repeat the preceding one last time, still using the 3 domino setup, but remove the disk and replace it with a piece of paper. You need time only 5 intervals, but if you prefer you may use 10. Enter your 5 (or 10) time intervals using the same format as before.
Your answer (start in the next line):
.108
.103
.989
.110
.104
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Do your results support or fail to support the hypotheses you stated in the first two questions, regarding the relationship between time intervals and slopes? Explain.
Your answer (start in the next line):
My results obtained in this experiment support my hypothesis made in the beginning two lines. As the ramp height increases, the time gets faster with the slope increasing too.
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How do you think the average velocity of the ball is related to the slope of the ramp? Explain in as much detail as possible.
Your answer (start in the next line):
I think that the average velocity is highly correlated to the slop of the amp. The formula for average velocity is a change in position over a change in time. The change in position for the formula is the height of the ramp, so as the position changed from increasing or decreasing the number of dominos under the ramp so too did the time change for the ball to hit the end of the ramp.
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Speculate on what it is that causes the average velocity on these ramps to change with slope.
Your answer (start in the next line):
I think the cause of the change in average velocity to change in slope was the number of dominos under the top of the ramp making it steeper or less steep.
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How might you verify whether your speculations are indeed valid explanations?
Your answer (start in the next line):
You can verify the explanations by finding the average velocity using the times obtained in the time intervals and the change in position by measuring the length of the ramp. From the equation you should be able to see a slight change with the average velocity.
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Do your data conclusively show that the disk made a difference?
Your answer (start in the next line):
The data shows that the disk may have made a slight difference because adding something underthe ramp slightly leves the ramp more making it less steep.
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Do your data conclusively show that the piece of paper made a difference?
Your answer (start in the next line):
The piece of paper I believe was too small to raise the ramp to level out the slope and did not make a significant difference.
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Imagine that someone is placing different objects below the 'low' end of the ramp, and you are timing the ball. Assume that somehow the object placed below the 'low' end is hidden from you in a way that does not interfere with the timing process. Compared to the thickness of the DVD, how thin would the object have to be before you would be unable, using the TIMER, to observe a difference in times down the ramp?
Answer this question in the first line below. Express your answer in multiples or fractions of the thickness of a disk.
Starting in the second line, explain how you came to your conclusion, based on the results you obtained in this experiment. Also discuss how you could modify or refine the experiment, still using the TIMER, to distinguish the effect of the thinnest possible object placed under the 'low end.
Your answer (start in the next line):
½ cm, 1 cm, 1.5 cm, 2 cm, 2.5 cm
I wasn’t too sure how to come up with these fractions. But I think that you would be able to tell the more significant difference between 1.5 cm and 2 cm. The disk did make a small difference but I believe that the ramp woud lhave to be lifted a little bit higher to about 2 cm to level out the ramp slowing the rolling ball.
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I believe that raising an end 1/2 cm would make a very clear and significant difference in the observed times.
A change of 1 millimeter might not be observable.
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Had you placed the disk below the 'low' end of the ramp in a 1-domino setup, do you think the difference in times would have been greater or less? Do you think you would be better able distinguish the presence of a thinner object using the 1-domino setup, or the 3-domino setup? Explain your reasoning below:
Your answer (start in the next line):
I think that in this scenario the difference would have been greater with one domino under the ramp. I think that you would be able to distinguish a greater difference with the one domino under the ramp. This is because with only one domino under the ramp the change in position would be less than the change in position with 3 dominos. However when you try to leveled the ramp platform out by placing a disk underneath the ramp with one domino the platform will be closer to leveled compared to a disk being placed under the three domino ramp.
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Does the ball's velocity change more or less quickly with the 3-domino setup or the 1-domino setup? Explain as best you can how you could use your results to support your answer.
Your answer (start in the next line):
The balls velocity would change more with the one-dominos set up with the disk underneath the short end because the change in position of the ramp would be the more significant causing a larger degree of change in the velocity equation of change in position over time.
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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?
Your answer (start in the next line):
This experiment took me about 1.5 hours to complete.
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*#&!
&#Good responses on this lab exercise. See my notes and let me know if you have questions.
Revision isn't requested, but if you do choose to submit revisions, clarifications or questions, please insert them into a copy of this document, 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. &#