Phy231
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.
** #$&* Your general comment **
3/7/10 8pm
** #$&* Will a steeper ramp give greater or lesser time? **
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.
The ramp with the steepest slope will have the fastest time because the slope will cause the acceleration to be greater.
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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.
The time intervals will decrease because the steeper the slope the faster the time because the steeper slope will cause the acceleration to be greater.
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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.
34cm
3.766s
3.391s
3.844s
4.109s
3.906s
1.688s
1.469s
1.797s
1.875s
1.594s
The first line is the length that the golfball is travelling. The first five times are the ball rolling from left to right. The second five times are from the ball rolling from right to left. I'm assuming that the times are faster for the ball rolling right to left because the table isn't completely flat.
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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.
1.469s
1.5s
1.5s
1.563s
1.453s
1.234s
1.235s
1.109s
1.422s
1.125s
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Repeat the preceding using 3 dominoes instead of 2. Enter your 10 time intervals using the same format as before.
1.141s
1.125s
1.234s
1.125s
1.172s
1.016s
1.047s
1s
1.172s
1.047s
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Do your results support fail to support the hypotheses you stated in the first two questions, regarding the relationship between time intervals and slopes? Explain.
They support my hypotheses. The steeper the slope the faster the times have been.
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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.
Average velocity is 'ds/'dt. The displacement is staying the same, but the speeds are increasing. So the average velocities are increasing with the steepness of the ramp.
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Speculate on what it is that causes the average velocity on these ramps to change with slope.
The ball moves easier down the slope when it is steeper. Gravity is pushing it down. The steeper the slope the faster the ball moves.
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How might you verify whether your speculations are indeed valid explanations?
I guess I could verify my speculations by timing various different slopes. If the ramp was completely level the ball shouldn't move at all because it won't have any force pushing on 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?
45min
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&#Very good responses. Let me know if you have questions. &#