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# Rube Goldberg Machine

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by

## Beth Warrington

on 11 March 2014

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#### Transcript of Rube Goldberg Machine

Step fourteen
Jenga blocks displace a marble, resting on an elevated cardboard maze, made up of inclined planes. The marble goes through it. Newton's First Law, as the marble is at rest, until acted upon by the jenga blocks.
Step One
The toy car hits the cup, which is supporting a sock full of marbles, acting as a weight. When the cup is hit out from under the sock, the 'weight' falls. The weight is attached to a ruler, in front of a bus. The weight pulls the ruler with it.
Step Two
The sock weight is attached to a ruler, preventing a bus from rolling down a ramp. Once the weight falls, the ruler is pulled up, and the bus accelerates down a ramp (inclined plane). This is mainly Newton's second Law, as the bus accelerates and then uses its force to knock down cups.
Step Three
After the bus accelerates down the ramp, it knocks over or displaces a cup tower, pushing the cups forwards. Newton's Second Law - bus's big mass and acceleration create a large force, knocking the cup tower over.
Rube Goldberg Machine
The top cup has a string wound around it, with stored mechanical energy in the form of tension,which is pulled. When the potential energy in the top cup is transferred to kinetic energy as it falls, the string is tightened.
Step Five
Step Four
The string's other end is taped to a cardboard disk, resting atop a funnel. As the top cup falls, it pulls the cardboard disk, and a marble sitting on a slit between the cardboard and the edge of the funnel drops. So once again, transferring potential energy to kinetic. Also Newton's First Law, as the marble is at rest, and stays at rest until acted upon by an outside force - gravity.
Step Six
The marble goes through the funnel, down a sort of maze. The maze is filled with a series of inclined planes. Gravity is acting upon the marble, causing it to move downwards.
Step Seven
The marble exits the 'maze', with a large velocity as it accelerates down the maze. It transfers its kinetic energy to a line of jenga blocks, starting a chain reaction. This is Newton's Third Law, because the blocks exert a force on the marble, and the marble exerts an equal force on the jenga blocks. Since the mass of the marbles is larger than the jenga blocks (there are two marbles), it causes the blocks to move.
Step Eight
The jenga blocks hit a roll of toilet paper off of the edge of a table, pulling the roll. The end of the toilet paper is stopping a marble from rolling down a ramp. When the toilet paper falls, the marble accelerates down the ramp, changing potential energy to kinetic.
Step Nine
The marble rolls down the ramp, and into a paper cup. This cup slides down a string and hits the dominoes. Some kinetic energy is transferred to thermal energy, due to the friction between the cup and the string. So the cup has less kinetic energy towards the end, and slows down. This is Newton's First Law because the cup is at rest, until acted upon by the force of marble rolling down the ramp.
Calculations of Potential and kinetic Energy For Step #3

One potential calculaton
mass=0.5597 kg
*Height= 0.267 m
*Gravity=9.81

Potential Energy= 1.47 joules

Step ten
The cup hits a line of dominoes, transferring its kinetic energy to the dominoes. The dominoes fall in a sideways direction
Step Eleven
Step Twelve
The dominoes fall sideways and up a hill, displacing a marble in a sideways direction. Newton's Third Law, the marble and jenga blocks push on one another with an equal and opposite force. Jenga blocks have more mass, so they dislace the marble.
Give two examples of where you had to overcome
Newton’s First Law of Motion to get your machine to work:

Newton's First Law says that an object in motion will stay in motion, until acted upon by an unbalanced force. So we had a roll of toilet paper that needed to be moved, but it was at rest, so it would stay at rest. We had to overcome this challenge by finding a object with enough strength, to cause the toilet paper to move. We finally found that jenga blocks did the trick!

In our zip line step, we found that the friction from the actual zip line (yarn) and the cup, was transferring all of the cups energy from kinetic to thermal, stopping the cup from moving. So a force, was acting upon our object, stopping it from staying in motion. We fixed this by finding a new material for our zip line - string - which has less friction when the cup runs down it.

Newton’s Third Law of Motion? Was there a place where the machine did not have enough strength to give “equal but opposite force?”

One of the steps that demonstrates Newton’s 3rd law is when the marble runs down the upright maze and hits the jenga pieces. This demonstrates Newton’s 3rd law because there is equal and opposite reaction because when the marble hits the jenga piece the jenga piece hits back on the marble. The jenga blocks move forward, due to the reaction force. At first, the marble did not have enough mass to knock over the jenga blocks. So we added a second marble. The combined masses was enough to knock down the jenga blocks.

A cup is pulled by hand, displacing a sock weight in a downwards direction due to gravity. This is Newton's first law because the cup is at rest, until acted upon by the force of someone pulling it out.
Distance=0.9 m
/ time= 1.02
(0.88235294117647) squared
0.77854671280277
*0.5597
0.43575259515575
/ 2

Kinetic Energy= 0.21787629757786 joules

The marble rolls down a series of pipes, with increasing velocity, and then slows as the pipes become less inclined.
Step thirteen
The marble hits a jenga block, which knocks down a series of blocks, up another lego 'staircase'.

mass=0.5597 kg
*Height= 0.267 m
*Gravity=9.81

Potential Energy= 1.47 joules
Step fifteen
Step Seventeen
The lever pushes down on an alarm clock, and turns it off. A race car's stored energy is also released on the other side or the lever, and the race car accelerates away (kinetic energy).
The marble exits the maze, hits dominoes, and kinetic energy is transferred through the dominoes.
Step Sixteen
The dominoes knock into a cup, displacing it sideways, causing it to fall onto the end of a lever. This changes potential energy to kinetic, as the cup falls down.
A kinetic energy calculation of the bus:
One potential energy calculation of the bus's energy.
Energy transfers
Describe a situation in which you needed to play with the balance of F = ma. Did you need to increase the force of some object hitting another to overcome its mass? How did you increase acceleration?

We had to mess around with the mass of the marble that was supposed to fall into the cup that would send both the cup and the marble inside the cup down the zipline. Our problem was, a marble with a large mass would shake the ramp it rolled down, causing the cup to fall prematurely. And a marble with a small mass, would not move the cup when it fell into it. Our solution was to have two smaller marbles, that did not shake the ramp, but had just enough mass and acceleration combined to knock down the cup.

Describe a transfer of mechanical energy (kinetic into potential, or visa versa) within your design using the terms “energy storage” and “energy release”.
A transfer of potential energy to kinetic energy is when the bus travels down the ‘road’ ramp in the very beginning of our machine. The bus is being stopped from traveling down the ramp, by a metal ruler, at the top of the ramp. This is stored potential energy, or energy storage because the bus is lifted against gravity. At it’s highest point, the bus has 1.47 joules of stored potential energy (mass x gravity x height = 0.5597 kg x 9.81 m/second^2 x 0.267 m). Then, when the bus is released, there is also energy released, as the potential energy is transferred into kinetic energy while the bus moves (mass and speed).

If we added more power to your machine, but changed nothing else, describe what we might see. Try to focus on places within you machine that this extra power could cause a transfer to fail. Explain why it would fail in the way you described.
Power is the rate at which work is done, so work/time. If there was more power in the machine, then that would mean that it would go faster, because it would be a bigger rate of which things are being displaced. You would see things speed up, and the machine would be over more quickly. In the step where a cup travels down a zipline, we depend on a low amount of power. We need less power because the marbles will sometimes move the ramp, and the cup will start to fall. However, the marbles still have time to fall into the cup, giving it enough weight to knock down the jenga blocks and dominos. If the cup step had more power, and the cup fell off the ramp faster, without the marbles, then it wouldn’t have enough weight to knock over the jenga blocks.
How does an understanding of science inform the choices made by an engineer? (ie how did understanding science help you with your build choices?)

Much of the science used in our Rube Goldberg Project, had to do with energy and forces. So building a machine required scientific knowledge. For example, the higher you set a hill, the more potential energy an object at the top will have, so the more kinetic energy it will have when it falls. Also, if we want to slow something down, you need to lower the potential energy, by lowering the height then object starts at. When we transform an energy, that energy is not created or destroyed, so the total energy in our machine should be constant. Engineers must keep energy transformations in mind, when building machines. This is because if a lot of kinetic energy is transferred to thermal energy, they could end up with no kinetic energy to complete their machine. This is just one example, but it shows how important knowing about science is for an engineer. This also helped us with our build choices, because we wanted some objects to go down ramps, and the higher the ramp, the more kinetic energy the object will have.
A ramp example:
Conservation Of Energy
The Law Of Conservation Of Energy states that energy cannot be created, nor destroyed, only transferred. So the total amount of energy in our machine stayed the same, but was transferred from kinetic to thermal to potential, etc. One huge consequence of this law, was that a lot of our energy was transferred to heat, due to friction. So some steps in our machine (such as the zipline) were slowed down because there was less kinetic energy. This was a challenge when we wanted to move objects with a greater weight, because we needed kinetic energy, but some had been lost.
Sarah is a high school student, studying for her SAT's. Her Sunday studying ends up taking longer than she expects, and she stays up until 3 in the morning! The next day, she is so tired, that she sleeps through her alarm clock. Her mom finds her five minutes before school, still in bed. Will she make it to school in time?
Story
Conclusion
Susan made it to school just in time for her first test! That was a close call.
Potential to Kinetic-cup
Potential to
kinetic-sock
Potential
to kinetic
-ruler
Potential to kinetic-bus
Potential to kinetic- Cups
Full transcript