Background:
A Rube Goldberg machine is a deliberately over-engineered machine that performs a
very simple task in a very complex fashion, usually including a chain reaction. The expression is
named after American cartoonist and inventor Rube Goldberg. The group had to have a
minimum of 4 energy transformations. Some examples of this would be potential, kinetic,
rotational, heat, and wind energy. The definition of a energy transformation is the capacity to
produce changes within a system. The group also had to find the efficiency for each energy
transformation and the formula for that is Work Out divided by Work In. The group understood
the concept that the overall efficiency of the machine will be low due to the fact that the
materials used were recyclable. A lot of research was performed on this project before a actually
sketch was drawn. The initial plan was to have 6 energy transformations, including wind energy.
However, it would be difficult to find the efficiency of the fan that supplied the wind. The team
also realized that a bag could be taped on the fan, which will inflate and tip over the water in the
water bottle in the water wheel. There was an electrical source of 9V,which could be used power
a fan. From that moment research was performed to find the formula for wind energy and it was
(d)(D2)(V3)(C). In this formula “d” represents the density of the air and D represents the
diameter of the fan blades. In addition to this, the V is the velocity that the wind is moving and C
represents a constant, which is 0.005. The formula for work is FxD when F is equal to force and
D is equal to distance, it is measured in joules. Some of the prior background research preformed
was on the different types of ideas on YouTube. Some of the machines used a fan on the top of
the ceiling and many of the machines used Lego toys. Also most of them had some type of ramp.
There was one design which was creative because they used a milk carton as a pulley system;
they also used cereal boxes to heighten the structures. The goal was to create a water wheel to
have hydro energy; the problem statement stated that there was a gallon of water to work with.
Completed some research on it to generate the type of materials that could be used. A water
wheel is a machine used to converting the energy of falling water into useful forms of water. The
idea was that the force of water would pull the string, which would trigger the hammer. The
hammer then would hit the car and push it a meter. The car had to go 1 meter and decided to be
on the safe side by putting sand in one of the cans, which was used during the testing process.
The initial predication was that it will make the car go faster. However, the car was jumping up
of the ground due to the strong force acting on it and was smacking into objects in the machine,
which was against the constraints. You could not touch or affect the car in any way in the meter.
Another part of the project research was completed on was what the base could be made
out of. The answer that came up was cardboard. The positive effects of this are that cardboard is
a recyclable material and can be easily glued together by using a hot glue gun. However, the
problem was the design that was constructed implemented a water wheel, which obviously has
water. After many trials the cardboard became vulnerable and would collapse the entire
structure. Cardboard takes a while to actually have water damage. So if the water spillage from
the water wheel is cleaned up quickly there would be no damage to the structure. Some research
was done on the durable cardboard compared to the other types of cardboard. From there the
thick cardboard on the bottle of the top base and had the light cardboard (cereal boxes) on the top
of the base. this was done because it was the only way the structure would stay stable. Also it
makes sense to put a lesser weigh piece of cardboard in a higher weight piece of cardboard. Also
another thing researched was how to make a durable structure out of recyclable materials. The
best solution to this was to use soda cans and hot glue them on top of each other. This would
provide a steady structure, which would not easily fall down. The group was also thinking about
rotational energy because this occurred when the fan was turned on. However, the fan we used
required us to break the fan to actually find the efficiency. Thus, a formula for rotational energy
was looked up and it was KER=½(I)(ω2). In this formula, there were two aspects hard to
understand. The first was “I”, which stands for moment and after some research was founded on
the formula for it is I=1/3mL2 when “m” is mass and “L” is length/distance traveled. The second
aspect of the KER formula was the “ω”, which stands for omega, the formula for this is d/t when
“d” is distance and “t” is time. The potential energy formula is mass*gravity (9.8)*height. This
formula was used to find the water calculations.
The group regretted not using additional forms of energy, so we came up with spring
energy. The prior knowledge from physic stated that a spring can be either stressed or
compressed. The spring was placed behind the car to hopefully increase the velocity of the car.
The formula for spring energy is 1/2kx2, when “k” is the squish distance and “x” is the force
acting upon the spring. Another problem was encountered, the water bottle was first placed
vertically and when the bag inflated to tip the bottle the water would never land in the water
wheel. Thus, the bottle was placed in a horizontal position. Therefore, the water fell into the
funnel which then poured onto the water wheel which solved our problem. Also the hammer had
such a string force that it would sometimes hit the top part or other cans on the machine. The
cans would become dented so cardboard was placed as a substitute for a protective barrier and
worked fairly well. Research was completed on how to keep something steady and in place like a
swinging hammer. a metal rod was attached and pieces of a straw on both sides so the hammer
so it would go in the same direction every single time. This greatly increased the chances of the
machine making the car move the required meter.