Phy 231
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.
** #$&* Your general comment **
** #$&* Will a steeper ramp give greater or lesser time? **
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 time required to roll down the ramp will be the least for the steepest ramp. This is because that ramp has the greatest slope and causes the ball to accelerate more because of gravity. Therefore the ball will go faster and go down the ramp in the least amount of time.
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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 for the increasing slopes will be decreasing. The gentlest slope will have the least acceleration and the ball will go the most slowly down it, so that it will have the slowest time. On the next slope the ball will travel a little bit faster and finally, on the steepest slope, the ball will travel the fastest and have the shortest travel time.
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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 so 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.
1.545
1.466
1.482
1.513
1.467
1.638
1.607
1.763
1.607
1.654
The data above illustrate the time it takes for the ball to roll down the incline with a slope of .03. It was collected by starting the timer program when the ball was released to begin rolling and stopped when the ball hit the bracket at the end of the incline.
The numbers are the time interval for each test that can be used to calculate velocity and acceleration. You have to be sure to release the ball from the same spot each time and not shorten the time interval by starting the clock late or stopping it early.
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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.
1.155
1.061
1.123
1.076
1.076
1.092
1.232
1.217
1.107
1.123
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Repeat the preceding using 3 dominoes instead of 2. Enter your 10 time intervals using the same format as before.
.858
.982
.889
.952
.904
.858
.936
.967
.936
.967
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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.
My results support my previous conclusions that the steepest slope will have the shortest time interval and the smallest slope will have the longest time interval. The time for the slope with one domino was around 1.6 seconds. The middle slope, with 2 dominos, was around 1.1 seconds. The steepest slope had the shortest time interval around .9 seconds.
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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.
The average velocity of the ball will increase as the slope is increased. This is because the ball is subject to faster acceleration as it rolls, so that it picks up more speed. This causes a greater final velocity greater, causing a higher average velocity because the initial velocity is 0. Another reason the average velocity is higher is because, on the higher slope, the same change in position is being divided by shorter and shorter times. This makes the calculated average velocity much higher than on a smaller slope.
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Speculate on what it is that causes the average velocity on these ramps to change with slope.
On a steeper slope the ball is better able to accelerate with gravity because it does not have to roll more horizontally to follow a gentle track. Instead, the ratio of vertical travel to horizontal is higher (higher slope) which allows the ball to be affected faster by gravity. This accelerates the ball more and causes the average velocity to be higher.
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How might you verify whether your speculations are indeed valid explanations?
You can test this by measuring the time interval for the ball on the same distance for a bunch of different slopes and for a vertical drop. The steeper the slopes go, the higher the average velocities should be because the acceleration is affecting the ball more and faster. Conversely, as the slopes get smaller, the average velocity should decrease because the acceleration is not as fast.
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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?
40 minutes
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&#Very good responses. Let me know if you have questions. &#