Science of Disney · Uncategorized

Science of Disney: Drop Rides

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Two of the most jaw-dropping Disney attractions – the Tower of Terror and Guardians of the Galaxy: Mission Breakout! – employ some plussed up elevators for an exciting and sometimes nauseating ride experience. Dropping 13 stories at a speed faster than freefall requires some pretty interesting science!

The Ride Vehicle

Most of the sources I consulted say that the Guardians of the Galaxy gantry lift or Tower of Terror elevator is an example of a simple traction elevator. Traction elevators operate as pulley systems. For Disney’s versions, each elevator shaft has two “drums” or wheels with cables running over them attached to motors located on the top floor. The cables from one drum are attached to the elevator vehicle or “cab”; the cables from the other drum are attached to a counterweight. Another set of cables is attached to to the bottom of the cab, goes around another pulley wheel at the bottom of the shaft and is attached to the bottom of the elevator cab.

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This design is pretty clever because it relies on a few laws of physics to reduce the amount of electricity required to run it! If we want to move the elevator up, we have to do work (a formal concept in physics, not like the chores that Cinderella did every day) in order to increase its potential energy. The physics concept of work is the amount of force applied across some distance: if we want to move the elevator up 13 stories (or about 130 feet) we have to put in a lot more work than if we wanted to move it 13 inches. The force that is applied across that 13 stories or 13 inches would have to be equal and opposite to the weight of the cab full of people.

The counterweight helps reduce the amount of force and thus the amount of work that the motors have to generate because gravity pulling down on the counterweight does some of the work for the motor. Gravity pulling down on the counterweight causes a force on the cables that is in the same direction as the elevator cab going up. But usually this counterweight doesn’t have as much mass and therefore not as much weight as the elevator, so the motor has to do the last bit of work to pull up on the cables attached to the cab.

For the cab to be “dropped” down the shaft, gravity could do all the work, but that wasn’t enough for Disney Imagineers. For the fall, an engine generates up to 1200 volts of electricity (10 times the electricity in a standard American outlet) to spin the motor in the opposite direction and pull down on the elevator. Combining this additional pull from the motor-driven cables accelerates the cab at a rate faster than gravity which makes for a shriek-worthy sensation.

 

The Experience

In real life, many people are scared of the possibility of an elevator plummeting to the ground, no matter how matter whether its 13 stories or just 3. But it is much more likely to wind up stuck in an elevator (sorry for the claustrophobes out there!) than it is to have an elevator crash all the way to the ground because there are elevators are equipped with so many back-up systems to prevent them from falling. Elevators only need one functioning cable to operate normally but they usually have at least three (each Disney ride elevator has five). Even if all of the cables were to be non-functional, which is highly unlikely due to regular maintenance checks on the wear and tear of the cables, each elevator has two braking systems which are also examined routinely. One braking system works to stop the motor from spinning and the other stops the elevator from falling by extending a brake into the guide rails of the shaft.

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Even going into the ride knowing that the ride is totally safe, the feeling of freefall can be quite frightening. Freefall is the name for when the only force acting on an object (for example, 21 human bodies in a metal box) is the acceleration due to gravity (32.2 feet per second per second) but we know from our exploration above, that the elevator falls even faster than freefall due to the motor putting in work. The elevators on Guardians of the Galaxy and Tower of Terror reach speeds of 39 miles per hour!

I have to save the science behind the magic of the Fifth Dimension portion of Tower of Terror at Disney’s Hollywood Studios for another day, but comment below with which version of this terrifying tower ride is your favorite!

Citations

Short & Sweet Stats

Translation of a German Film about Paris’s Tower Construction

More on Elevators

More on Tower of Terror Motors

Explore more Physics!

How Counterweight Works Mathematically

More Fun

Tower of Terror Simulation Game

Science of Disney · Uncategorized

Science of Disney: Smellitizers

From the sweet wafting of vanilla on Main Street, USA to the slow burning of wood in Spaceship Earth and the barrage of ocean breeze and orange groves in the various iterations of Soarin, Disney employs some relatively simple technology to enhance the sensory experience of their park and make your memories that much stronger.

How do Disney’s scent machines work?

Disney’s scent machines, often referred to as smellitizers or smellitzers, are used throughout the parks in various attractions, including but not limited to Soarin’, Spaceship Earth, Living with the Land, Stitch’s Great Escape, Journey into Imagination, and Muppets Vision 3D to accompany sights and sounds and make the attractions feel much more realistic.

These smellitizers are descendants of Smell-O-Vision which was used in movie theaters in the 1950s but quickly declined in popularity. Smell-O-Vision in theaters failed because the mechanism detracted from the movie-watching experience: the fans used to dissipate the scents were loud, covering up the music and dialogue, and the scents took too long to dissipate to the audience so that they were not synced properly with the film.

Imagine not smelling the dirt from Mt. Kilimanjaro until the Paris scene of Soarin’ – doesn’t really make you feel like you are transported to either locale, does it? What’s so special about Disney’s technology is that the smells are timed precisely, released relatively discreetly and directly, dissipate quickly and can be used repeatedly for around 80 to 100 showings a day per theater.

Put simply, Disney’s machines involve programming a container of a scented substance to be positioned in front of a fan and turning on the fan to blow air across the substance and toward the audience. This process works because of how chemicals become airborne and how we smell, explained below.

What causes smell?

We can only smell substances that are sufficiently volatile. Volatility doesn’t mean that the substances are evil or mean like Scar or Maleficent but rather, a volatile substance has a tendency to vaporize, or turn into a gaseous form. We are only able to smell things when the molecules that make them up are in gaseous form because only gases can reach the space in our skull where we detect smells. But how do substances that are not gases to begin with transform into gases?

Typically, substances transition from liquid into gas form, like when we boil liquid water and it turns into water vapor. Similarly, scented candles distribute scent by heating solid wax first into a liquid and then into a gas. But liquids are difficult to control in machinery, thus smellitizers are not likely to use substances in liquid form.

Because we are still able to smell the scents of things like candles, soaps, and solid air fresheners even when they are in seemingly solid form, is there another way that smellitizers could achieve their desired effect? Yes! They could either rely on containers of chemicals in gaseous form already or on a process of transforming a solid into a gas called sublimation.

Sublimation requires very special conditions depending on the material in order for the molecules in a solid to have enough energy to become a gas. Heating a solid air freshener is one way to cause sublimation and distribute scent but I think it is unlikely that Disney uses nearly constant heat in all of its smellitizers if it can be avoided because of the high cost of supplying enough energy for such a process. Furthermore, regular life experience seems to indicate that solid air fresheners work pretty effectively even when not in a heated location. Thus, alternative materials or conditions need to be used to make a solid substance in a smellitizer smell.

The most likely explanation is that blowing cool air over the scented substance (typically composed of volatile organic compounds) with a fan lowers the air pressure above the scented substance by blowing away the molecules that were present before. The same process is at work when wind blowing over a puddle causes the puddle to evaporate more quickly. With fewer molecules present above the scented substance or puddle, more molecules can escape into the air. More molecules turning into gas form results in a higher likelihood that we will detect a smell.

How do we smell?

Chemicals from smell-producing objects travel through the air, into our nostrils (or through our mouth and to the back our throat), through our nasal cavity until they reach a section of the nasal cavity called the olfactory epithelium. The olfactory epithelium is a membrane covered in mucus that traps the chemicals for smell and is littered with 40 million olfactory neurons. Each of these neurons has special proteins in their membranes which function like locks that are only opened by the proper smell molecule key.

After the molecule unlocks all the receptors that it can, the neurons with those receptors activate and send a signal to a different part of the sensory nervous system called the olfactory bulb, which is just a bundle of neurons. In addition to sending the signal from the olfactory bulb straight to the olfactory cortex (where higher-order processing occurs), the signal is sent to both the amygdala, which is responsible for emotions, and the hippocampus, which is integral for memory formation.

Why is smell so powerful for triggering memories and emotions?

The several neurons activated by a smell’s molecules are usually arranged in a particular spatial pattern in the olfactory bulb that is gradually (through repetition) associated with the object that caused the smell. This recognition is how a memory for a smell is formed, just like the activation patterns associated with the color red in the visual cortex or our friend’s voice in the auditory cortex are paired together over time. Because we have more types of receptors for smells (at least 350!) than we do for sight, our memories for smells can be much more specific and also require less complicated integration of sensory information. This specificity may be one of the reasons why we can recall a more specific set of memories from a smell than from just an image (such as a photo of a perfume bottle or the word “rose” instead of the smell associated with each).

Additionally, there are fewer steps involved in the pattern recognition of smells (through the olfactory bulb then to the cortex) than the pattern recognition of sights or sounds (which must first go through a traffic control center called the thalamus). The sensory pathways for smell are much more integrated with the amygdala and hippocampus than other sensory pathways, which likely served our ancestors well in their survival: having a better memory for smells of predators and dangerous foods would prevent death.

Furthermore, smell memories are some of the best-preserved over time. If the first time a memory for a scent is formed occurs during childhood, positive emotions associated with nostalgia can make that memory even more powerful. This may explain why the faintest smell of a churro can bring me back to walking along the Rivers of America in New Orleans Square and why I burst into tears when the Disneyland 60th Anniversary fireworks were accompanied by gingerbread scented “snow” that reminded me of baking gingersnaps with my grandmother.

What scent (Disney or non-Disney) is the most powerful for you? For me, it’s the smell of oranges from Soarin’ and the smell of fresh-cut grass from home.

 

Citations

Patent for Soarin’ Ride System

Patent for Soarin’ Smellitizer

Illustrated Video of Smell by Ted-ED and Rose Eveleth

History of scent-emitting technology

Linda Buck’s Nobel Prize Acceptance Speech Transcript for Smell Receptors

Arshamian A, Iannilli E, Gerber JC, Willander J, Persson J, Seo H-S, Hummel T, & Larsson M. The functional neuroanatomy of odor evoked autobiographical memories cued by odors and words. Neuropsychologia 51 (2013), 123-131.

Where to Buy Disney Scents (not sponsored)

Walter and Rosie Candle Co.

WED Way Candle Company

Science of Disney · Uncategorized

Science of Disney: California Screamin’ / Incredicoaster Launch

Tantalizing trills of a triangle, a cadence of carnival bells, then a countdown – 5…4…3…2…1! – and the screaming begins.

California Screamin’ at Disney’s California Adventure closed January 8th, 2018 and was re-themed with an Incredibles overlay to become the Incredicoaster. Today, I’ll explain some science concepts integral to the launch of this awesome ride.

How does this coaster launch you from 0 to 55 miles per hour in under 5 seconds? Most roller coasters rely on a motor and chains to pull the train up a lift hill (the initial tallest hill) to provide enough potential energy to make it all the way around the track, but The Incredicoaster manages to send a train around the longest looping roller coaster track (6072 feet!) without a mechanical lift hill. Instead, this roller coaster uses a linear induction motor. How does a linear induction motor work? In a few words, with high-powered electromagnets and electromagnetic induction. To explain further, let’s review some basic physics.

How do magnets and electricity work together?

Charges (like electrons) moving together in one direction, like in a wire conducting electricity (literally the movement of electrons) create an electromagnetic field around the flow of charges. When two magnets or two electricity-carrying wires creating electromagnetic fields are brought close to each other, the electromagnetic fields between the two electromagnetic objects combine depending on the direction. If the fields are going in the same direction, the force created by the field is stronger between them; this occurs when magnets of the same polarity come into proximity with one another. When the two fields are going in opposite directions, a weaker force is created like when you combine a negative number (-5) and a positive number (7) to get a number that has a smaller absolute value (2) than either original number; this occurs when magnets of opposite polarity come into proximity with one another.

Like in other domains of physics and chemistry, an equilibrium, in this case of forces, is the most stable and thus desirable state. In order to get rid of the stronger or weaker forces, the magnets want to move to a state of equilibrium. When magnets of the same polarity create a stronger force between them, moving away from or repelling each other leads to an equilibrium state.

How does the Incredicoaster use electromagnetism?

The launch system for the Incredicoaster employs this idea of movement as a result of repelling magnets to move the train forward. There are several slots in the track of Incredicoaster that have electromagnets (unclear whether these are coils of wire or metal plates) with current flowing in one of three states (inward direction, outward direction, or not flowing at all) regulated by switching on and off a connected battery at different times. This battery is controlled such that each small section has an electromagnetic field going in a different direction from the section adjacent to it.

After the train is in position on the launch section of the track, the electromagnetic fields at the beginning of the launch section are turned on by “a 25-megawatt transformer [feeding] a 5,000 horsepower variable frequency drive” in a “100-yard-long room beneath the ride” according to this New York Times article. The magnetization of the track causes movement of electrons in a metal blade attached to the bottom of the train so that the electrons align with the electromagnetic field of the track. This movement within the metal blade creates electromagnetic fields within the metal blade called eddy currents. The electromagnetic fields of these eddy currents interact with the electromagnetic fields of the track to create repulsions and move the train forward. This process continues as the current in each section of track cycles through each possible state (in, out, or off). The wheels of the coaster keep it guided along the track as the train picks up speed with each subsequent repulsion and the riders shriek with delight (or fear).

The same process is at work when the coaster needs to pick up speed over the highest hill after the launch as well as any time the coaster needs to brake (although in this case, the electromagnetic fields work to push the coaster in the opposite direction, effectively slowing it down).

Can you guess which other Disney rides use this same technology?

 

 

Helpful Videos

 

PhD Life · Uncategorized

PhD Friday Week 1 Synthesis

For the past few months, I’ve been in a rut regarding my research topic. On one hand, I feel like I am just scratching the surface of an immensely large body of literature on analogy and comparison for learning in laboratory and classroom settings, which makes is both overwhelming and motivating. But on the other hand, I also feel like pursuing my current line of research is too theoretical and not preparing me for the kind of career I want to impact learning beyond the classroom by designing educational technology.

After reading the papers I summarize below, I feel like I’ve finally had a breakthrough that can combine both my theoretical and applied interests. In addition to helping me think of some new research ideas, I think the learning principles discussed are relevant to teachers and learners outside of academia. I look forward to discussing any ideas that the following article summaries make you think about!

Gamification of Cognitive Training 

Two different protocols of working memory training using an N-back task led to mostly similar improvements and performance on transfer tasks. As expected, participants reported being more engaged and expending more effort in the gamified condition of the N-back task which was designed to have more motivational elements than the non-gamified condition. Participants in the gamified condition showed greater improvements in working memory after four training sessions than did participants in the non-gamified condition.

My Two Cents: This paper harkens back to an early stage of my research career when I was completing an honors thesis on the psychological construct of executive function, which includes working memory, inhibitory control, and switching ability (which is kind of a combination of the other two). Although I focus less on these psychological constructs now, the principles for what makes a good game are relevant citations for me to follow up on when I design my own educational software.

Variation Theory

The authors outlined some tenets of variation theory that inform the selection of examples for instructional purposes. Variation theory recommends a progression of examples that first enable contrast, then generalization and then fusion. What this means is that students need to see non-examples as well as examples to illustrate the important point that a teacher wants them to learn. For example, it is hard to know what defines a triangle until a triangle is contrasted with a square or a circle. Then after seeing several examples of triangles being contrasted with other things, you learn each of the properties that makes a triangle special. Combining all of these triangle properties helps you understand the concept of a triangle. In the rest of the paper, the authors detail what is made possible to be learned (different from what is actually taught and what from students learn from a lesson) through a teachers’ selection of examples and tasks in two different lessons on solving equations.

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My Two Cents: This is where my breakthrough started to materialize even though the paper was still very much focused on in-classroom learning. Variation theory is basically what all of my ideas about why comparisons are important boils down to and I have yet to see it explicitly implemented in educational technology.

On top of giving a very applied explanation of how variation theory might be used to plan a lesson, this article happened to be in a special issue that includes other articles I was excited about: applying principles of cognitive psychology to teaching. Even though the other articles in the special issue barely mentioned variation theory, they all seemed to fundamentally depend on these ideas.

Example-based learning, self-explanation and comparison

Example-based learning is the idea of providing students with a set of examples that helps them develop the common procedural or conceptual thread between them. Different from traditional math instruction in which a teacher demonstrates solving several math problems in the same way, example-based instruction would be more akin to a student looking over the worked out examples and the explanations for each step in a textbook. In his article on example-based learning, Renkl made the case that this technique is most effective when students engage in self-explanation while they are studying the worked examples, especially when students are new to the material.

Self-explanation was a separate technique further outlined in another article by Rittle-Johnson, Loehr & Durkin (2017). In contrast to a common practice in several math classrooms in which the teacher has the main responsibility for explaining the reason for a problem-solving step or the principle that two problems have in common, self-explanation is when students do this work themselves. The greater mental effort expended by the student when self-explaining helps improve retention over hearing someone else explain. However, students need to be trained in how to do high-quality self-explanations. Unfortunately, not much detail was provided on how to do this besides

These two techniques were combined in a chapter on comparisons more broadly. Durkin, Star & Rittle-Johnson (2017) acknowledge that there are several types of comparisons that are beneficial for learning depending on what is being compared and what question is asked. Comparing an incorrect solution with a correct solution (an example of example-based learning) is beneficial but is more beneficial for students with higher prior knowledge who are better able to distinguish the important differences and figure out the reasons why one is correct (self-explanation). For students who are less experienced with material to be taught, it is more helpful to compare the same solution method for multiple problems in order for them to gain confidence with one method before introducing them to alternative methods for solving similar problems.

My Two Cents: I see each of these techniques relying on variation theory. In order to have effective example-based learning, examples that highlight different and similar features need to be carefully selected. Prompting students to make comparisons helps draw attention to these differences and similarities as well as encourages them to explain their reasoning for why these differences and similarities exist.

Which principle is most relevant to your teaching and learning experiences?

Citations

Durkin, K., Star, J. R., & Rittle-Johnson, B. (2017). Using comparison of multiple strategies in the mathematics classroom: Lessons learned and next steps. ZDM, 1-13.

Kullberg, A., Kempe, U. R., & Marton, F. (2017). What is made possible to learn when using the variation theory of learning in teaching mathematics?. ZDM, 1-11.

Mohammed, S., Flores, L., Deveau, J., Hoffing, R. C., Phung, C., Parlett, C. M., … & Zordan, V. (2017). The benefits and challenges of implementing motivational features to boost cognitive training outcome. Journal of Cognitive Enhancement, 1-17.

Renkl, A. (2017). Learning from worked-examples in mathematics: students relate procedures to principles. ZDM, 1-14.

Rittle-Johnson, B., Loehr, A. M., & Durkin, K. (2017). Promoting self-explanation to improve mathematics learning: A meta-analysis and instructional design principles. ZDM, 1-13.