Warren Edmunds
Scott Cramer
EF 151
Final project report
Summary
Our machine, named “the almost incredible machine” is a Rube Goldberg device that
utilizes potential energy to complete the task of lifting a one kilogram weight one meter in 10
seconds in a very inefficient manner. The machine uses a combination of gravimetric and kinetic
energy to complete the required task. The machine works in three steps to complete the task.
The steps are the following: 1. A line of dominoes fall on an elevated platform, the last domino
hit’s a golf ball. 2. The golf ball rolls down a downward sloping series of tracks. 3. The golf
ball hits a stick that is holding a counter-weight on a lever. The stick is knocked out of the lever
mechanism which allows the counter-weight to fall, and the counter-weight lifts the 1 kg mass
using a pulley.
Design Process
We strived from a design that was simple, inefficient, and effective. We were concerned
that an overly complicated design would be unreliable in completing the final task of lifter a 1 kg
weight 1 meter in as close to 10 seconds as possible. The required budget of 20 dollars also
influenced our design. We used house hold objects such as scrap wood, a Tupper-ware
container, a golf ball, and duct tape to build our machine. The premise of a Rube Goldberg
machine is to utilize potential energy, and set up a device that is initially triggered then a series
of inefficient steps happen to complete a end task. We decided to use gravimetric energy as our
main potential energy because it is simple and very reliable. With all these things in mind our
group worked together to first sketch out the design, and then build our machine.
What We Built
We built the machine primarily out of scrap wood. Each component of the machine was
attached to a 1 m by 0.5 m wooden base. The elevated platform designed to hold dominos was
first cut to size, then two supports were attached to either end of the platform using wood-glue,
and finally the structure was attached to the wooden base also using wood-glue. We glued small
square bosa-wood dowel pieces on to the platform to make a place for the golf-ball to rest (figure
1). The next step was to build the tracks that the golf-ball is to roll down. The three tracks were
make from sections of a 2’’ by 1’’ piece of wood. Pieces of the square dowel were cut to size,
then attached with glue to the edges of the track to make rails for the ball to roll on. Supports
were cut to size and attached to the tracks. Then we marked the angles for the three sections of
track, and attached them to the wooden base. A wooden backstop was added to the second track
to prevent the ball from rolling to far in that direction. Parts of the railing were raised with extra
pieces of bosa-wood to prevent the ball from rolling off the tracks (figure 2). The last step was
to build the lever structure and counter weight. A piece of wood was attached to the base to
serve as a fulcrum for the lever. The lever is a rectangular piece of wood. A wooden structure to
hold a small stick pushing down the lever to prevent the counter-weight from falling was built.
This stucture was carfully positioned so that the golf ball would roll and knock the stick out of
the holder, and the structure was attached to the wooden base. The counter weight was precisely
calibrated to the correct weight so that when it fell, it would lift the 1 kg mass in about 10
seconds (figure 3). Finally, the counter-weight was attached to the 1 kg weight with a string
through a pulley system that was provided.
Figure 1 - elevated domino platform
Figure 2 - tracks
Figure 3 - lever, trigger
Summary of Energy
Golf ball rolling down track: gravitational energy (mass*gravity*height ). There is energy loss
in this system if the form of friction between the ball and the track, but we can not measure this,
so we are assuming no energy loss from friction and air resistance.
0.04593 kg * 9.81 m/s2 * 0.457 m = 0.206 N-m
Golf ball hitting the stick supporting the lever for the counter weight: kinetic energy
(0.5*mass*velocity2) We have no way to measure the speed of the golf ball when it hits the
stick, so we are going to estimate a speed of 0.75 m/s.
0.5 * 0.04593 kg * (0.75m/s)2 = 0.0172 N-m
Counter weight falling and pulling up 1 kg mass: gravitational energy (mass*gravity*height )
1.25 kg * 9.81 m/s2 * 1 m = 12.2625 N-m
Bill of Materials
*wood- found around the house- free
*2 pullies - $4.00
*duct tape - $2.50
*wood glue - $2.00
*dominoes - $5.00
*golf ball - $.50
*string - $.50
TOTAL: $14.50
Conclusion
Our project was definitely a success and we learned quite a bit in the process. By success
I mean that the machine successfully worked in the way that we wanted it to. Making the
machine work the way we wanted to was the hard part. We encountered several unforeseen
complications in the design of a machine like this. Simply figuring out a design was challenging
enough by itself. Construction of the basic design was not very difficult but concentration on
details was critical to make everything come together and work as it should. After completing the
construction and seeing the other groups’ designs, I don’t think we would change anything. Our
design was not extremely complicated, but it worked. A simple machine that consistently works
is definitely better than a complicated but inconsistent design.
Sources
All of our ideas and designs involved with our project were original. We did not use any
outside sources for help.