Introduction - Engineering Fundamentals Program · Introduction The objectives of the Engineering...
Transcript of Introduction - Engineering Fundamentals Program · Introduction The objectives of the Engineering...
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Introduction
The objectives of the Engineering Fundamentals 151 team project was to create a model
roller coaster spending less then 40 dollars in materials, building the model in a 0.5 meter by 0.5
meter by 0.5 meter maximum size limitation, and consistently executing a minimum of a 15
second trial roller coaster run. Our team had very little problem satisfying the parameters of the
material costs and size dimensions, but the time limit wound up being the toughest objective to
complete. The roller coaster we created was very inconsistent at first with problems in the tubing
and speed. When we first started building the coaster, the circumference of the tubing was larger
making the speed of the marble be faster. This made our roller coaster too fast and hindered our
goal of meeting the minimum time limit. As the days went by in the construction of the roller
coaster, the circumference of the tubing slowly decreased to the point of making the marble have
such a low velocity that it would come to a complete stop. Using all of our basic knowledge of
Physics taught to us by Professor Schleter and Dr. Arazi and brainstorming, we were able to fix
these problems and create a very successful model of a roller coaster.
Design Process
The engineering design process is a specific process in which a problem is derived from a
need, and after large amounts of research, brainstorming, and adjusting of the product a solution
is made. The problem defined for this project was to build a roller coaster that is simple in built,
reliable in execution, and consumes around 15 seconds during its run time. Each member already
had their own ideas of what to use for track and how to make the roller coaster so the next step
would be brainstorming. The group came together with different sketch ideas, all revealing the
ideas of several spirals and a jump in order to take up 15 seconds and yet still have a fun
conclusion to the roller coasters run. After the group decided on one specific idea it was time to
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actually build the project. As the project grew the ideas for how it should be built changed with
each new problem that presented itself until the final design was complete, similar to the original
idea but perfected through the experienced gained through trials and error.
Device
The Rocking Roller Coaster that Symbolizes the UT Football Season’s original design
was one of simplicity devised to do the two things that were specified in the project layout, to be
simple and consume as close to 15 seconds with its run as we could. Our team’s first idea was to
make a rather high, main post to support a long track of tubing that would spiral down at an
increasing angle until the ball plummets to a ramp. Our idea was to use undone wire hangers
secured to the main post to hang the spiraling tubing. It soon became evident that the size of
tubing we needed to use would weigh too much to be held up by just the wire, and the set up
time it would take would inevitably exceed the allotted 30 seconds specified in the project
guidelines, so a new idea was introduced. The group agreed on sticking with the long spiral idea
ending with a jump, and rather than using the hangers as support we decided to split the main
post half way up and set it up like a field goal post in order to have a sturdy support post on each
side of the loops.
As the group came closer to finishing the roller coaster several problems began to come
up. One main issue was that the tubing being used had a tendency to pinch down on the ball in
several areas slowing the ball down and occasionally stopping it altogether. The first idea to
remedy this problem was to use splints to pinch the tubing the other way, but with the tube
constantly spiraling the splints would just get in the way. The next idea was to use duct tape to
squeeze down on the tubing in a way that it would hold it in a rounder position. A similar
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problem was of the tube kinking at the points where it rounded the support arms as we added on
more spirals to the project. This problem was solved by using the left over wire hangers, left over
from our first idea, as support for the tube’s integrity at these critical points. The wire was bent
into coils the size of the tube and then placed at the critical points to support the tube at the
problematic pressure points. The rest of the project fell together as it came closer to being
finished. Wood platforms, cut for a 45 degree angle, were used for the ramp and a funnel was
used to catch the ball at the end to catch the ball, and send it through more tubing to its finish, a
Mellow Yellow can. With the project near completion timing became a real issue. How the
project was designed at this point it was running at a max of 13 seconds, something more needed
to be added, but the ball had no more energy after jump to go through more loops and we were
out of tubing. The only idea that seemed possible would be to add tracks to the top that were
slightly slanted, just enough so that the ball could roll from one side of it to the other. In the end,
two tracks were added to the top of the roller coaster and the device was timing out at just over
15 seconds.
After we built our roller coaster, we ran several test runs to determine the distance that
the ball travelled through the air after the jump. After we determined how far the ball would
travel, we decided to determine the ball’s velocity as it left the ramp. To do this, we made all of
the necessary measurements and used the trajectory equation to solve for velocity.
Eq. 3-36
Next, we decided to determine the theoretical velocity that the ball would have if it did
not have any energy losses due to friction. To do this, we used the conservation of energy
equation.
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Eq. 7-9
Then, we used the conservation of energy equation again with the actual recorded
velocity in order to determine how much energy was lost to friction.
Eq. 7-9
When it came to the graphs we used in Matlab, we used the trajectory equation to create a
graph of the distance versus time plot (Figure 1).
Eq. 3-36
Then, we used constant acceleration equations to create the y-component velocity graph
and the total velocity graph (Figures 2 and 3).
Eq. 2-21
Eq. 2-23
Here is our parts list with prices:
Parts List
10ft. sch40 PVC ¾ in. $ 2.19
2 sch40 elbows ¾ in. $ 0.58
1 sch40 tee ¾ in. $ 0.33
20ft. vinyl tubing ⅝ in. $ 8.00
Duct tape $ 3.00
Hardware $ 1.00
Wood $ 5.00
Hot glue $ 1.00
Coat hangers $ 2.00
2 Ball bearings $ 0.50
Mello-Yello can $ 0.10
Funnel $ 2.00
Spray paint $ 3.44
Can of compressed air $ 8.00
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Total $37.14
Results
0 0.2 0.4 0.6 0.8 1 1.2 1.40
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Bearing Trajectory
Distance (ft)
Heig
ht
(ft)
Figure 1. plot of the trajectory of the ball with distance as the x-axis and height as the y-axis
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0 0.05 0.1 0.15 0.2 0.25 0.3 0.350
1
2
3
4
5
6
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time (seconds)
speed (
feet/
second)
Y-Component Speed Time Plot
Figure 2. plot of the y-component of the speed with respect to time
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0 0.05 0.1 0.15 0.2 0.25 0.3 0.354
4.5
5
5.5
6
6.5
7
7.5
time (seconds)
speed (
feet/
second)
Speed Time Plot
Figure 3. plot of the total speed of the ball with respect to time
Conclusion
The design of our roller coaster seemed simple enough, however, while building it we ran
into unforeseen problems and delays. The total time we spent building the roller coaster added up
to about 12 hours, which was much more than we had expected to spend on it. The project was
frustrating at times due to the problems encountered, but it was a nice change from the usual
classroom environment. This project was useful in providing us with real world application of
the concepts learned in EF 151 and served as a grand finale to the semester.
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References
Fishbane, Paul M, Stephen G Gasiorowicz and Stephen T Thornton. Physics for Scientists and Engineers.
3rd Edition. Upper Saddle River: Pearson Prentice Hall, 2005.
Pgs.: 41, 69, and 187
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Appendices
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