FINAL PROJECT REPORT
Google Docs. can be found in this link (much easier to read):
Moais are very large sculptures made of stone found in Easter Island, an extremely isolated island found over 3500 kilometers off the coast of Chile. The Rapa Nui, the original inhabitants of Easter Island, are known to have built these immense statues throughout their history. However, how the Rapa Nui transported the moai and what eventually led to the demise of this population is largely a mystery to many historians. We know today that moais were on average fours meters high and weighed approximately 13 tons each, which means they must’ve been incredibly difficult to transport with the little technology we assume the Rapa Nui possessed. The moais were built in small groups of people using volcanic rock from a quarry at the center of the island, and transported over a few kilometers to the coast, where they were positioned to face inward towards the island. The question of how they were moved has been debated a number of times. Some historians claimed that they were made to roll on the trunks of trees found throughout the island. Yet further research suggests this wouldn’t have been possible, as the enormous statues would’ve crushed the tree trunks. Some people liked to claim that it would’ve been impossible for the Rapa Nui to transport them without extraterrestrial help, stating that extraterrestrial beings moved the moais, although most of us have a hard time believing this theory. The most credible and widely supported theory, however, emerged four years ago. Some university students and researchers conducted trials to see whether instead of being moved horizontally, the statues could’ve been moved vertically. A replica of the moais was created, and then, using two ropes and a relatively small group of people on each side of the statue, the moai was made to “walk” on its base. Although this theory seems quite plausible, some still argue that they weren’t moved using this method, and the way the moai were transported is still debatable.
The history of the island and the apparent demise of its population is also perplexing. The Rapa Nui appeared to have arrived on Easter Island sailing for thousands of kilometers from a Polynesian island. The year they arrived isn’t certain, but most would agree that it was somewhere around 300-400 AD. The history of the island is generally divided into three phases: the early period (700-850 AD), the middle period (850-1680 AD) and the late period (1680 and on). The early and middle periods are known to be the most affluent and culturally active of the history of the Rapa Nui. It’s in these periods where most of the moais were constructed and moved. They were thought to be meant for religious purposes, to serve as a link between the living and the dead for the Rapa Nui. The Rapa Nui are said to have thought that they were the last inhabitants of the world, and the statues face inwards to protect the islanders. This reflects the isolation the people of the island lived in, and suggests that they never expected visitors to the island. Later on, however, evidence seems to point at the fact that the island underwent a period of devastation. The late period appeared to be characterized by violence between islanders and starvation, which would later lead to the demise of the island. Additionally, some historians suggest that the eventual downfall of the island was caused by ecocide, meaning for some reason the islanders eventually exhausted all of their resources. Later, explorers would arrive in the island, and their testimonies would corroborate the theory that a civil war ravaged the Rapa Nui population. A large part of the island’s culture was destroyed.
In order to help preserve the culture and history of the island, the Chilean government has asked us, Stainless Inc., to help transport one of their moais using our excellent knowledge of Physics and our experience working with moais. Before doing so, however, we decided to make a small-scale plan for the transportation of the real-sized moai. The objective of this project is to specify how exactly we would move a newly made moai from a quarry on top of a hill, down a hill, and across a rough terrain to an ahu. This will not only help us in accomplishing the transport of the Chilean government’s moai, but it may also hint at how the Rapa Nui managed to move their moais, possibly providing new historical insight.
The first step to building the transport design was planning out what our terrain would be like. We decided we would make the base of the terrain out of wood, which we would later cover in turf to create a more realistic replica of the terrain the Rapa Nui would’ve been working with. Previous to building, Anna the data manager, figured out the exact sizes of the wooden planks we’d need, and got them cut to size to make the building easier. Arnau, the website manager, who is notably good with technology, made a design of the terrain on the computer to help us better visualize what it should look like. The wood we used was very strong and 0.3 cm thick. The entire structure was 35 cm tall. There is a 10 cm wide platform on top for the moai to stay on before it is transported. The ramp is approximately at a 37 degree angle with the base. The only problem with the ramp is that it is longer than it should be. We made it approximately 58 cm long, when its maximum length was supposed to be 30 cm, and despite the fact that it didn’t fit the guidelines it was okay. Although that makes transport slightly harder for us, we can work around it. The base was 106.5 cm long in total, and the ramp structure took up 56.5 cm of that, so the flat terrain that remained after that was 50 cm long. Our first moai, which according to some looked like an old man, was 11 cm tall and weighed 391.9 grams. On our terrain covered with turf, this moai had a mu of approximately 0.3. However, this moai would unfortunately break later on during a trial, and the dimensions of our new moai are a slightly different. Our new moai is 9.5 cm tall, and 386.4 grams in mass (Fg = 3.79 N). The force of friction of our terrain is 2.2 N, which means the mu of the moai on the terrain is 0.58. This is a significant amount of friction, and it is also part of the reason why we chose not to slide the moai directly on the terrain.
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2.2 N friction to overcome
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Mass = 386.4 g
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W = 3.79 N
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Mu = .58
No matter how the moais are transported, it all runs heavily on physics concepts. Our transport method starts with Newton’s First Law, where an object at rest, in this case the moai, wants to stay at rest, unless an unbalanced force acts on it. The first obstacle the Rapa Nui would have had to overcome was how to get the moai onto the transport. Our solution to this issue was to use man power, with ropes, in order to lay the moai down on its side and also to do the same to the truck. This way we could easily tie the moai down and bring the truck back up in the same way. At this point we would have to make sure the truck is properly attached to the pulley system before we begin moving it down the hill. This means we have to overcome the structures inertia. When the structure is at the top of the hill, it has gravitational potential energy that we need to convert to kinetic energy. To start the truck’s motion, we need to begin with pulling on the bottom pulley to overcome the static friction of the truck and moais combined mass. We know that the Mu of the moai on our terrain is .58 which is relatively high, so using the truck with wheels helps lower that because the material results in a lesser friction. Once we get the truck in motion, the pulley at the top of the hill would be used to control the velocity and acceleration of the truck. We cannot have it moving too quickly or slowly to avoid putting the moai in danger. The most difficult part to control will be moving it down the hill, because the force of gravity will want to make our structure accelerate, but we cannot allow the gravity to overpower us. Our goal would be to keep the whole structure of the cart and the moai in equilibrium as much as possible. This means that ideally, the net force would be 0 N to keeping it at a constant acceleration the entire time. Once we make it to the bottom of the hill, using the pulleys will be a simpler system because gravity is no longer an issue. Now that we are at the bottom of the hill, all we have to do is pull the structure over to the ledge that will be used to leverage the structure over and allow us to drop the moai right onto the ahu. Our original plan was for the Rapa Nui to be able to use the equivalent man power of 22 Big Teds, but that didn’t work out as well. Now we have modified and the Rapa Nui would have a hydraulic lift on hand to be able to leverage the truck over the ledge. Then, all that is left is to untie the moai and he has been safely transported to his new home. Yay Hex!
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Overall, our group worked quite well together. The few arguments we had throughout this process were geared only towards making the transportation of the moai better, and at all times criticism was constructive. We can all agree that we were very open-minded throughout and listened to each other's’ ideas. We were a well-balanced group in that each one of us is radically different from the other, and we all provided completely different insights on how to do certain things and come up with solutions to existing problems. As a group, we worked very well and complimented each other nicely, however, there are some things that we could’ve done differently to improve our transport design. Our group had a large number of ideas, and we built a few options, but we never tested them out. When we built our final design, we noticed, very near our deadline, that it did not work. If we’d been testing this throughout, we would’ve known ahead of time and we would’ve been able to fix it a long time before the deadline. However, since we didn’t really do that, we had to change some parts of our design near the deadline. The new design did work when we tested it, but redoing so much of our work caused an immense amount of stress. Other setbacks like the demise of our original moai also made finalizing the project extremely stressful. The fact that we had a new moai with a different mass and different dimensions also made it difficult for our transport mechanism to work as we’d hoped it would. Had we gotten a more stable cart earlier on in the process, a relatively simple solution, many of our problems later on wouldn’t have taken place. We put a lot of effort as a whole into this project, but sometimes our efforts were geared in the wrong direction, or we were so fixated on getting certain things to work that we completely forgot about other elements we should’ve taken into account.
In conclusion, this moai transport project made Stainless Inc. realize how difficult it must’ve been for the Rapa Nui to move their moai, with the numerous complications this entailed and the lack of technology they were working with. It was a difficult project for us because it required many new skills that other projects have not required of us. One of the skills that we’d like to highlight, that we believe we’ve all improved in a lot, is constancy throughout the semester. This project was one that required steadiness and perseverance through the course, and we learned that it is essential to maintain focus and work ethic in every single work class for a project of these characteristics to be a success as a whole. Another difficulty we encountered was that of making decisions. We had an immense number of choices to make in this project, and they weren’t always easy. It was hard for us to make decisions as a group when we could see deadlines nearing and stress increased, but even so, we found ways around our problems. Despite the obstacles we encountered, we are very proud of how we came together as a group, and despite the end result not being exactly the way we wanted it to be, we are proud of the way we worked together throughout the course of this project.