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phy121
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 **
sept 22, 10:50pm
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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 ball will roll the fastest down the steepest ramp. I think this because the force of gravity is greater on the ball, and the downward force on the ball to a steep ramp is greater thus meaning a quicker time down the ramp.
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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):
If we wrote down the slopes next to the time intervals, we would see the time intervals decrease from least steep to the steepest. There is more of a force downward on the ball and less friction when the ramp is steeper which would mean that the balls speed would increase as the ramp got steeper.
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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):
1.828s
1.875s
1.891s
1.828s
1.859s
2.297s
2.344s
2.531s
2.141s
2.297s
This data shows the time interval from release to the end of the ramp to hit a bracket. The first 5 are the ramp pointing one way, and the second 5 are for the ramp opposite direction. The TIMER system was used and was started as soon as the ball was released at the top of the ramp and was stopped as soon as it hit the bracket at the end of the ramp. I was thinking that the ball would roll, but not roll fast down the ramp since the incline was not that tall. However, I was not expecting the times to be different between one side than the other. However, the 5 on the first side are relatively constant to each other, and the 5 on the second side are relatively constant to each other as well.
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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):
1.266s
1.297s
1.266s
1.297s
1.297s
1.391s
1.578s
1.430s
1.563s
1.406s
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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):
1.094s
1.094s
0.984s
1.031s
1.063s
1.055s
1.094s
1.094s
1.102s
1.102s
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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):
1.188s
1.172s
1.156s
1.141s
1.172s
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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):
1.094s
1.094s
1.155s
1.155s
1.141s
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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 support my hypotheses regarding time and steepness of slope. It showed that the steeper the slope, the faster the time between the other heights of slope. Three dominoes was the fastest, followed by 2 dominoes and then a single domino. I predicted that the time was decrease (speed of ball increase) as the slope of the ramp got steeper.
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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):
The average velocity is related to the slope of the ramp by saying that the greater the slope of the ramp, the greater the average velocity will be. As we can see, as the slope increased, the times sped up to go down the same ramp. If we find average velocity by displacement/time, we can see that as the ramp increases, so does the average velocity.
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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):
The reasons why average velocity changes in respect to slope is because the force of gravity is acting on the more. As the ramp increases, less of the ball is touching the ramp (not by much) and creating less friction (again not by much). But if we look at the ramp as a triangle where the ramp is the hypotenuse, then the greater the height of the ramp, the greater the angle of the ramp will be.
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How might you verify whether your speculations are indeed valid explanations?
Your answer (start in the next line):
Since the force of gravity is always the same, we can calculate by it by thinking it like a projectile, since it is “falling” in an aspect. We can also do the same experiment at the same heights with different materials that provide more friction acting on the ball and less friction acting on the ball, compared to the metal ramp we used in this experiment.
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Do your data conclusively show that the disk made a difference?
Your answer (start in the next line):
Yes the disc did make a difference. It was not a big difference, but the times were a bit slower to go down the ramp. With the disc being there, the angle of the ramp was slightly less than before, which made the ball take just a little longer to roll down.
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Do your data conclusively show that the piece of paper made a difference?
Your answer (start in the next line):
Again, the paper did not make a huge difference, but it made a difference in time. The ball rolled faster than it did with a disc under the ramp, but just a little slower than without the paper under the ramp. Again the angle of the ramp was changed ever so slightly to create to ball to move not as fast down the ramp.
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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):
I would first measure how many stacks on paper is equal to the thickness of one disc. Let’s just throw a number out to be relevant. Let’s say 6 pages on paper is equal to the thickness of one disc. By looking at the times of the objects, I would have to say “is that 1/6th the speed of the disc? Or 1/3? Or half? Or 2/3/ or 5/6?” and calculate the time difference and see which object is which and which object is thicker or thinner.
It is all about angles, the greater the angle at the bottom of the ramp, the faster the ball will roll down the ramp. By placing objects underneath the bottom of the ramp, it is, in retrospect, evening out the ramp. The more you put at the bottom, the more the ramp becomes “level” and you can put the same amount of objects under the end of the ramp as the beginning of the ramp and it would be level. By changing the angle, even so slightly, it changes the speed of the ball rolling down the ramp. I would modify this experiment by putting dominoes on the end as well to show students that when the angle changes, the speed changes. By just showing that one side of the ramp is raised then they automatically assume that the ball will speed up. I would try to change their thinking and place objects of equal or near equal on both ends and have them calculate the angle of the ramp and show them that even a change of 1 degree can lead to a different time with the TIMER program.
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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):
If the disc was placed under the end when there was 1 domino, I would expect the ball to take a little longer to get down the ramp as the angle has decreased. I think if we were still using one domino and put a piece of paper under the end, I don’t think we would see that much of a difference. The reason being because the angle is already low with only 1 domino, and changing the angle from a piece of paper would not be enough to change the results. Since 3 dominoes already have a greater angle, the slightest lift of the bottom end of the ramp changes the ramp angle more than we think, thus changing the time.
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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 changes more quickly with 3 dominoes than the 1 domino setup. Because if we take the average velocity of each setup by finding displacement (which should be constant for both setups as the ramp length doesn’t change) and the time it took to get down the ramp, you would see that the balls velocity is greater in the 3 domino setup than the 1 domino setup, thus a greater average velocity which would me a greater final velocity in the 3 domino setup. Because both setups start from rest, so if the average velocity is greater, the final velocity would be greater as well.
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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):
50 minutes
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&#Very good data and responses. Let me know if you have questions. &#