The Trap
EF 151 Final Team Project
Justin Beau
Trevor Guydon
Andy Shoemate
Abstract:
The purpose of this project was to make a Rube Goldberg device while applying
at least five of the main physics concepts that have been taught throughout the
semester (choosing from projectile motion, torque, center of mass, and conservation of
translational energy, rotational energy, linear momentum, or angular momentum). A
Rube Goldberg device is an inefficient and complicated apparatus that completes a very
simple task. The device we must design must activate an electrical device at the end.
Exercising creativity, persistence, and a lot of trial and error is necessary to making sure
any Rube Goldberg device will perform with precision promisingly.
Introduction:
This project challenged our team to administer some of the most important and
complicated concepts of the class to a complex and real-world situation. The
objectives of this project provided applications to all of the concepts we went over, and
was extremely demanding in that we had to incorporate many of these concepts into a
single fully functional and reliable operating machine.
Our device utilized six of these seven main concepts; conservation of
translational energy, conservation of rotational energy, conservation of linear
momentum, torque, and projectile motion. Although it was quite the challenge, we
believe that we have successfully built a Rube Goldberg device.
Design Process:
We began simply brainstorming and listing ideas of what we would like to see
done. We concluded that we wanted some sort of pulley system, tubing with projectile
motion into a funnel, and that dominos needed to trigger our electrical device in the end
somehow.
Although we made a few alterations, our final product was a lot like the rough
draft. Both the rough draft and final product utilized six of the seven different concepts
that were taught. Conservation of translational energy occurs when the ball rolls into
the can, when the cup drops due to the weight, and when the final ball rolls and finally
drops onto the calculator. Conservation of rotational energy occurs because energy is
conserved with the movement of balls and weight, and the ball spinning in the funnel.
Conservation of linear momentum happens as the ball falls into the cup, and when the
dominos collide. Torque makes it appearance in the three pulley system. And finally,
projectile motion occurs when the ball shoots from tubing into the funnel.
Bill of Materials:
Total Cost: $18.39
-
Spaghetti can
[$.50]
-
Plastic cups (2)
[$.25]
-
String
[$1]
-
Tubing
[$3.25]
-
Funnel
[$.75]
-
Wood
[$2.25]
-
Dominos
[$1.60]
-
Styrofoam
[$.30]
-
Pulleys
[$1.25]
-
Zip-ties
[$.75]
-
Brackets
[$1]
-
Ductape
[$.75]
-
Glue
[$1]
-
Cardboard
[$.25]
-
Screws, nails, bolts
-
Iron Weight
[$.79]
-
2 balls
[$1.10]
-
Mousetraps
[$.60]
[$1.50]
Device Operation:
“The Trap” starts with a can at the upper-left hand corner of the board that
contains a fairly heavy metal ball. This can sits at its center of mass on a pivot system,
has a string attached to the front of it, and also represents the change from potential to
kinetic energy. The other end of this string is connected to a mousetrap, which initiates
the entire process. We placed a mousetrap on our design for when we have to activate
it ourselves, and worked things out with the group before us so that they were sure to
use a mouse trap at the end of their project as well.
When the mousetrap is activated and pulls the string, the ball located in the can
is released and falls into a cup that is about eight inches below the can. The cup is
attached to a string, and is the triggering point of the pulley system. The pulley system
contains a cup at the end of a string, which runs through three pulleys, and is connected
to a level platform at the end of it with one metal ball stationed on it.
The impact of the ball falling out of the can in the beginning into the cup triggers
the pulley system, and causes the ball that is stationed on the level piece of wood to
pop up into the air. The ball then lands into a two foot long tube. This curved tube
bends back towards the center of the design and projects the ball into a funnel that is
located about five inches away.
Once the ball enters the funnel, it spins around until it is finally shoots out at an
angle and hits a domino, causing a chain reaction of dominos. The dominos loop
around the bottom, and continue up a set of steps. These steps are the key to turning
on the electrical device. When the reaction reaches the top of the steps, it hits a ball
that has been patiently waiting atop. The falling domino causes the ball to roll down the
platform until it reaches a hole and falls through. This hole is about three inches above
the floor, and the calculator’s [ON] button is placed directly under it. The impact of the
ball falling onto the button turns the calculator on, and completes the cycle.
Results:
After many alterations, the device we constructed is very strong and reliable.
Thru the testing stages we ran into several problems, most of which the balls took part
in. We first had trouble getting the ball which was sitting on the flat platform to land in
the tubing. In order to fix this we took a paper cup and essentially made a funnel
around it. Once we got the ball in the tube, we ran into trouble with placing the funnel in
the correct spot to where it would catch the flying ball consistently. Correcting that took
a lot of trial and error. We also ran into some issues with the ball hitting dominos before
it was supposed to, as well as with the last ball not gaining enough momentum to fall
hard enough to turn the calculator on at the end. With much persistence, we adapted
designed a very reliable machine.
Conclusion:
We believe that we were successful in building an inefficient and completely
unnecessary machine. We ran into several issues on the way, and often got frustrated,
but when everything is done and over with we all agree that we had a great time and
that the work was well worth our efforts. If we could do anything differently, it would be
that we took a little more time in designing and building our machine so that we could
make it a little more complex. We originally had some great ideas that we ended up
having to throw out; such as dumping a bottle of water into a cup to activate the pulley
system instead of the falling cup. However, we learned precision takes patience and
that time often gets away from you (especially when you run into issues) and it can
drastically effect your decisions.
Calculations:
References:
-
Class notes on equations
-
Engineering Fundamentals Website (ef.engr.utk.edu)