ball down ramp

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Phy 121

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.

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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 believe that the ramp with the most incline will lead to the least amount of time taken for the ball to travel down the slope. As the slope is increased, the ball's average and max velocity are also increased.

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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 would expect the time intervals to be increasing as the slope increases. As the slope is increased, the ball's average and max velocity are also increased.

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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):

For this experiment I used my Physics book, and placed it long ways, with the domino under one end, with the 3 cm marked using a dry-erase marker. I collected the following results:

1 6056.805 6056.805

2 6058.531 1.727

3 6069.203 10.672

4 6071.836 2.632

5 6078.375 6.539

6 6080.969 2.593

7 6087.453 6.484

8 6090.031 2.578

9 6097.148 7.117

10 6099.789 2.640

11 6103.469 3.679

12 6105.961 2.492

13 6111.938 5.976

14 6114.039 2.101

15 6119.086 5.046

16 6121.461 2.375

17 6126.453 4.992

18 6128.867 2.414

19 6135.148 6.285

20 6140.305 5.156

21 6142.578 2.273

These values were collected using the TIMER program

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This information doesn't describe what you did or what your data mean.

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You haven't indicated which data correspond to the time intervals you are measuring. You've reported the unedited output of the TIMER program, which contains much more than the data requested.

I can of course figure out what everything means. You have ten time intervals between 2.3 and 2.6 seconds or so, and these correspond to five trials with the book in one direction, and five with that direction reversed.

The general reader would never figure this out. Your report needs to be written for the general reader.

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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 6383.336 6383.336

2 6384.875 1.539063

3 6386.977 2.101563

4 6388.492 1.515625

5 6390.688 2.195313

6 6392.242 1.554688

7 6394.18 1.9375

8 6395.516 1.335938

9 6397.766 2.25

10 6399.172 1.40625

11 6432.305 33.13281

12 6433 .6953125

13 6435.281 2.28125

14 6436.477 1.195313

15 6438.625 2.148438

16 6439.742 1.117188

17 6450.289 10.54688

18 6451.359 1.070313

19 6454.227 2.867188

20 6455.367 1.140625

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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 6597.211 6597.211

2 6598.18 .96875

3 6599.641 1.460938

4 6600.734 1.09375

5 6602.352 1.617188

6 6603.352 1

7 6606.023 2.671875

8 6607.578 1.554688

9 6608.766 1.1875

10 6616.984 8.21875

11 6618.516 1.53125

12 6620.141 1.625

13 6621.719 1.578125

14 6623.344 1.625

15 6624.969 1.625

16 6626.766 1.796875

17 6628.367 1.601563

18 6630.125 1.757813

19 6631.781 1.65625

20 6634.953 3.171875

21 6636.492 1.539063

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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 6705.898 6705.898

2 6707.828 1.929688

3 6709.5 1.671875

4 6711.531 2.03125

5 6713.484 1.953125

6 6715.273 1.789063

7 6716.945 1.671875

8 6718.797 1.851563

9 6721.18 2.382813

10 6723.039 1.859375

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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 6773.117 6773.117

2 6774.758 1.640625

3 6776.484 1.726563

4 6778.141 1.65625

5 6779.797 1.65625

6 6781.414 1.617188

7 6783.414 2

8 6785.102 1.6875

9 6786.906 1.804688

10 6788.531 1.625

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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):

As i predicted, the ball rolled down the slope faster with the more dominos underneath it. The slope increased the velocity and even when I placed the CD underneath the other end(using 2 dominos), it still rolled faster than when only 1 domino was used.

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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 of the ball is increased as the slope is increased. The ball is able to gain more momentum over time with a larger slope. This equals higher average and max velocities.

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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):

As the slope is increased, the weight of gravity upon the ball creates more and more momentum. This is the direct cause behind the speed increase. There are other factors that may come into play (for example, if the experiment was conducted in a fish tank.)

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How might you verify whether your speculations are indeed valid explanations?

Your answer (start in the next line):

Based on the shorter time intervals recorded above, it supports my theory of more slope = more velocity

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Do your data conclusively show that the disk made a difference?

Your answer (start in the next line):

Yes. It did slow down a little bit. It had 2 dominos, and the cd at the other end. This was slower than the 2 dominos alone, BUT was still faster than the 1 domino. It was in-between.

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Do your data conclusively show that the piece of paper made a difference?

Your answer (start in the next line):

No. There was no marked difference. The values of the timer were very similar to the ones taken without the paper.

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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 think that a thickness of 5 or more papers would cause a marked (and noticeable) difference. It may also be more benificial to the results to have one person manning the timer program while another rolls the ball down the ramp.

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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 believe the detection of the thinner object would've been more apparent with the 3 dominos instead of just 1 or two. With the CD , it seemed to roll noticably slower, even just to the eye alone.

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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 changed at a quicker rate with 3 dominos. The reason why is because the slope was increased; which lead to higher average and max velocities.

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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):

About an hour and 15 minutes

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You need to clarify all your data reports, all of which contain a lot of extraneous information not relevant to the interval you were measuring.

&#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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