Zombies. What does that term mean to you? Chances are you think about something from Hollywood. I actually thought that’s all there was to this Halloween character. I was wrong.
Zombies have a true biological basis to them. The stories as we know them have their origin in the country of Haiti. This small Carribean country is famed as being one of the only places where the African slaves revolted and kicked out the Europeans. After doing that, their African tribal culture took over. Many say it’s now more African than Africa! It’s also the epicenter of Voodoo.
When you think of Voodoo, think witch doctors. In fact, witch doctors are integral to the culture in Haiti and help create order. People are in constant fear there that the witch doctors may turn them into a zombie. They’re particularly susceptible if they’ve done something bad. Thus, the threat of zombification may keep some order.
Hogwash, you might say; it’s just crazy voodoo beliefs that have no basis. That’s what I thought until I read about a man named Clarvius Narcisse.
In 1980, the world got the first real proof that zombies existed. Clarvius, walked into a hospital one day claiming to be a zombie, and for the first time ever, there was proof that he was pronounced dead and buried. Turns out, it was at the same hospital he walked into. He even had a scar on his cheek from the nail they drove into his casket. He claimed that someone dug him up, beat him and drugged him for the last 18 years as he worked as a slave on a sugar cane field. So how did this happen?
To help solve this mystery, ethnobotanist Wade Davis immersed himself in the Haitian culture. After meeting with several witch doctors, he finally got his hands on a few “zombie potions.” To his surprise they all contained a similar toxin, known as tetrodotoxin. This came from the ground up remains of a pufferfish.
The story goes that a witch doctor would blow this potion onto a victim, and the toxin would start to take effect. It would drop the vital functions to such a low value that people would pronounce them dead, and they’d be quickly buried. Then, witch doctors would dig them out of the grave before they actually died. They’d beat them and make them work as slaves in a stupefied state the rest of their life.
The key to zombies though isn’t just the tetratotoxin; that just falsifies the death and helps give credence to the legends of zombies rising from the grave. In fact, a plant by the name of Datura, or the “zombie cucumber” (Datura stramonium) actually gives the stupefied state to the enslaved. Datura is a plant in the deadly nightshade family, related to mandrake and henbane (of werewolf legends).
The concoction I’ve just described though, isn’t a recipe for zombies. In fact, it’s not a good idea to replicate any of this. A dosage that is even a fraction too high would kill someone. In fact, it’s highly likely that 99 percent of witch doctor potions would kill someone. There are even a lot of critiques of Wade Davis that claim that none of the concoctions he presented could make a real zombie.
In the end, it might not really matter if this works in practice anymore. The zombie idea is so entrenched in the lore of the area and that might be all that matters. To Haitians, zombies are real. In the meantime, we can make them real in the movies. Just know that it all comes from what could be a very real biological basis.
In this ecofact we’re here to discuss how the legend of vampires may very well have arisen from a basic misunderstanding of human biology. Let us explain.
Corn, which was discovered in the new world, was brought back to Europe in the 1500s. It quickly became a crop of the poor, who would often eat nothing but raw corn as their main energy source. But, here is the problem. Corn contains the essential vitamin niacin, but it is inaccessible in its raw form. Thus, eating a diet of only raw corn leads to a vitamin deficiency known as pellagra. Victims of pellagra are hyper-sensitive to sunlight. If exposed, the skin often turns shiny with scaly areas. The brain starts to degenerate causing the person to have insomnia, anxiety, aggression, and depression. Often the persons stomach bleeds, meaning they can not eat normal food and can often digest only blood.
Here is another interesting tidbit: Pellagra was not common in the new world where corn was native. The reason for this is that peasants in Mexico and Central America prepared corn differently. Corn tortillas were often prepared with lime (an alkali)which helped to extract niacin from the corn and thus insured that pellagra didn’t arise.
We’ve all had the experience of standing around with a group of friends, trying to make plans for dinner. One person is a vegetarian, another a dedicated carnivore, while a third has a wheat allergy. Half the group lives on one side of town and is lobbying for a restaurant close to home, while the other half is already hungry and would rather not travel so far to eat. Reaching a compromise in a group with such different needs and preferences generally requires extensive discussion and negotiation.
Animal groups confront similar challenges every day, but can’t talk through their conflicts or debate their options. How do they reach a consensus about where to go and what to do? Do they vote democratically? Or does a despotic dictator make the decisions for everyone? To figure this out, we need to be able to track the movements and behaviors of an entire group of animals, simultaneously. High resolution GPS tracking technology–the same basic equipment that car navigation systems use—makes this possible.
The goal of this project is to capture and GPS-collar every member of a baboon social group, and track their movements and behaviors in very fine detail. These data will help us figure out if baboons vote and maybe give insight into how we as humans make decisions as well.
Researchers
Meg Crofoot
Meg is the lead researcher on the project and brings a great deal of background in primate behavior work. Most of her work has been on capuchin monkeys in Panama. However, with the technology available, this research question called for larger animals, and baboons fit the bill. Meg is currently a researcher with the Smithsonian Tropical Research Institute, the Max Planck Institute in Germany, and will be an Assistant Professor at UC Davis in 2013.
Roland is the director of the Lab of Biodiversity and Earth Observation in Raliegh, NC. He has research projects all over the world, all involving animal tracking. For this project, he came down to help assist Meg in the baboon trapping and help oversee the collar data collection.
Suzan Murray
Suzan is the lead veteranarian at the Smithsonian’s National Zoo, in Washington DC. She specializes on a wide range of exotic animals, and has been to Kenya for several years. During this study she took blood samples to study disease transmission in primates.
Matthew Mutinda – KWS
Matthew was the vet for the Kenya Wildlife Service, KWS, a team that helped coordinate the project with the Kenya government. Matthew brought with him several trapping specialists, who were vital to helping the project become a succesfull collaboration between all parties.
Robert Lessnau
When you get to know “Bob”, like we do, you’ll know that he’s the kind of guy that really doesn’t care about danger. He walks through elephant fences, and smokes cigars from the end of a burning log. Bob is a specialist in darting baboons and curator of mammals at the Detroit Zoo.
What is it like to be a field biologist?
A lot of students probably wonder what it’s like to do biological field research. In fact, most people probably have little idea what biologists do in the field. While field biologists are as diverse a bunch as you might get, Rob and Haley took a trip to the Mpala Research Station in Kenya to get a feel for one study in progress by a diverse crew of biologists.
In this ground-breaking project on baboons, the researchers are using cutting edge technology (GPS collars), and good old field research (tracking the baboons on a daily basis) to help ask how groups of animals make decisions. To do that, they needed to capture an entire troop of baboons and put these radio collars on them. It’s not as easy a task as it might seem.
This video should show your students a great glimpse into the world of field biology, which can be both difficult, and entirely thrilling at the same time.
We seem to be in a time of transition as of late, where the problems of fossil fuels are giving us an incentive to take up the drive for greener, alternative methods of energy. Ask anyone what those are and they’ll surely tell you about wind energy and solar energy. How many people would suggest energy from the ocean? Turns out, the first wave energy collection buoy was just deployed for commercial use in the US off the coast of Oregon. That’s big news. But, what does this really mean for us? That’s the topic for our weekly video!
We didn’t have time to explain all the energy sources possible from the ocean in our short video so we thought we’d expand on that briefly. Here are the most prominent examples of energy sources from the ocean.
Tidal Energy
Barrage Tidal Energy
The best example of this form of energy collection is in La Rance, France. There they have essentially built a barrier (barrage) across the river whereby they let water in as the tid flows up, and then harness energy from it as the tide flows out. In a recent report from the the European Union stated that: “Ninty percent of today’s worldwide ocean energy production is represented by a single site: the La Rance Tidal Power Plant (240 MW) that was commissioned in 1966. This type of installation has remained unique in the world and has only been reproduced at much smaller capacities in Canada (20 MW), China (5 MW) and Russia (0.4 MW).” “This type of project was abandoned for many years because of very high initial investment costs as well as the strong local impact that results from it. However, the present economic situation has encouraged South Korea to build a 260 MW dam closing off Sihwa Lake, which is set to be commissioned in 2009. Lighter new techniques, like hydro turbines, are being developed today to harness ocean currents. The leader in this field, the British company, Marine Current Turbine (MCT), should install 1.2MW in Northern Ireland following its 300 kW pilot project in Bristol Bay.”
Tidal Stream Energy Generators
Instead of building a barrage, which essentially acts like a hydroelectric damn, an alternative is to put turbines in the water. They’d act a bit like an underwater wind farm. Water is much denser than air and thus, a small movement of water could produce a lot of energy. Unfortunately, these devices are currently bit expensive and only generate electricity up to 4 times a day as the tide goes in and out.
Thermal Energy
Ocean Thermal Energy Conversion
The concept for this type of energy production is to utilize the thermal gradient in the ocean to create energy. Essentially the surface water of the ocean is very warm and the deeper you go it gets cooler. You could use the temperature gradient to heat up and cool down a gaseous substance like ammonia. The expanding gas could be used to power a turbine. Not all places are ideal for this energy production, however. It is important that there is about a 38 degree Farenheit temperature gradient between the surface water and the deep water for this to work.
Wave Energy
Wave Energy may hold the best potential for creating energy from the ocean. There are endless waves that pound the shore each year. Here are some of the basic forms.
Wave Energy Bouys
One of the simplest forms of energy generation is to have a floating buoy on the sea surface. While different companies have come up with different ways to use the up and down motion of the waves to create energy, we’ll highlight here the OPT buoys. The up and down movement of these buoys help turn a turbine, which generate electricity. This electricity is then sent to substation underwater, which is the then sent to grid onshore. One benefit is that the buoys can be set out and pulled in with minimal cost. The big news with energy buoys is that they represent the first wave energy devices available for commercial energy manufacture in the united states. In fact, along the coast of Oregon, the government has issued a permit for 10 energy buoys that should be enough to generate electricity for 1,000 homes.
Wave Energy Snakes
The company that has pioneered this version is Pelamis. They have a giant red snake that floats in the ocean to convert wave energy into electricity. The name Pelamis comes from the name for a surface swimming sea snake. The Pelamis snake generates electricity as the hinges move up and down. There is hydrolic fluid that moves back and forth moving a motor to generate electricity. The nice thing about this sort of energy aquisition is that you can have a bunch of snakes floating out at sea to generate a lot of energy wired back to shore.
Wave Energy causing Air Compression
If you’ve ever been to a rocky cliff zone and seen a blowhole, you will understand that the rising and falling of ocean waves along the cliffs, can force air rapidly up through the hole. This form of wave energy takes advantage of that concept. The first energy generator of this kind, the Limpet 500, was put into use in November of 2000 on the island of Islay off Scotland’s west coast. The only problem I see with using this form of energy generation on a grand scale is that it takes away the shorelines aesthetic value. One or two might not look so bad along a coastline, but imagine the entire rocky shoreline replaced with these concrete power stations.
Other Great Videos
This short video is one of the best I’ve seen to summarize all the different types of energy that could come from the ocean.
So you can’t really call it a garbage patch in any real sense of what we’d all imagine as a patch of garbage. In fact, it’s really more like a really remote place where you’re more than likely to see some trash floating around – in an area that you should never see trash … the middle of the pacific ocean.
Where is it?
Technically there are two patches, and eastern and western one. They’re formed by the North Pacific Gyre (which is the space in the middle of the current’s drawn). Note what else is in the middle of this gyre … Hawaii.
How big is it?
Defining the garbage patch is kind of tricky because there really aren’t a lot of people going out there to sample. Technically they are defining the region as anywhere that has more plastic than the average in the ocean. That means the entire gyre could technially have slightly more floating trash than average in the ocean. In my view, it’s not a great deffinition. But, that’s where you get claims that the “garbage patch” is twice the size of texas. Some even go as far as saying it’s twice the size of the US. Technically they would be correct. The problem is that the media jumps on these claims and overstates it. When people find out what’s really there, they start to doubt scientists, when it’s not scientists that are misleading anyone.
How much trash is there?
Don’t start thinking there is a visible patch of trash anywhere. Granted, if you were to sail through this area, you’d see a lot of floating debris (maybe 10 pieces a minute). But, most of it is tiny. You’d have to pick it up with a pair of tweezers they’re that small. The Manta Tows that the crew did pulled for an hour and a half. The images you see here are how much trash they collected in that time. It’s not as much as you’d think, given the headline, but remember, there shouldn’t be any out there.
What can we do about it?
Well, there really is no way to clean this up. It is mixed in to all the plankton in the ocean now and filtering it out would mean filtering out all the plankton too. So, that means that we’re really going to have to just think about how to stop the influx of trash into the ocean. Truth be told, I know the US let’s a lot of trash into the ocean. However, I’d be willing to say that this is a much larger problem. Just look at images you see from developing countries (I’ve taken a fair few myself). There is very little trash cleanup and thus, a LOT of their trash makes it into the ocean. That’s bad news for everyone. I say this so that you know I’m not blaming anyone here in the US. Obviously we can all do our part to use less and recycle, but even if one person every year accidentally looses track of ONE piece of trash, that’s six billion pieces of loose trash. We’re dealing with a problem of shear numbers here.
If you’re really passionate about this garbage patch, the whole effort has really been started by one guy – Charles Moore. You can read up on his mission here.
And below is a 12 minute Documentary by Lucy Marcus showing more images and science in the Pacific Gyre :
I’m a firm believer that you have to do what you love. I’m sure my colleague Jonas would agree with me here. It’s why I make science films and write profiles about plants and animals. There really isn’t a lot of money in it, but somehow we make it work. Recently, our accountant sent me this film. He said it made him think of us. As I watched it, I kind of teared up. I think you all might enjoy it as well.
As I watched this I could almost hear my brother telling me that I should get a real job (which he’s done multiple times). I remember when I was really poor, living on 1,000 dollars a month on a boat in the pacific – rent is free that way. I remember borrowing money from friends to get my cameras. I didn’t enjoy that part of it, but somehow I made it without loosing those relationships. I feel so lucky to be doing what I do. Now, I just hope that it’s useful for others as well. I hope you enjoyed this little video we found.
My name is Rob Nelson, and I’ve been interested in marine science my whole life. Fish were my world. However, sometime in college I remember thinking that I know nothing about plants. They became one of my newfound passions, leading me to film and document them for over 10 years now.
I can tell you that there are some amazing plants in this world. In the plant kingdom, most of us imagine passive green leafy-beings. I know I did. Not many of us think of them as invaders, murderers or traps. Yet, the plant kingdom contains just as many killers and oddities as one can find in the animal kingdom. In fact, I’d probably argue there are more. You see, plants can’t move, so they only defense is in the toxins they produce. While I want to profile all different types of this world’s wicked plants, I think we need to start simple. In this week’s science podcast, we’ve started by profiling the invasive plants…
My wife and I have recently teamed up with the North Carolina Arboretum to make videos for their Wicked Plants display, which included more of the world’s worst weeds. Check out the display here.
Finally, since my goal is to share some of the amazing plants of this world, I created this short list.
Top Ten Bizarre and Wicked Plants
1. The Largest Flower in the World
Rafflesia arnoldii: this parasitic plant develops the world’s largest bloom that can grow over three feet across. The flower is a fleshy color, with spots that make it look like a teenager’s acne-ridden skin. It smells bad and has a hole in the center that holds six or seven quarts of water. The plant has no leaves, stems, or roots.
2. The World’s Worst Aquatic Weed
Hydrilla:This little plant non-native aquarium plant was first introduced into Florida in 1960 and is now considered the most problematic aquatic plant in the United States. Management costs millions of dollars each year. Hydrilla’s dense mats suck out the oxygen, destroy fish populations and encourage mosquito breeding. It can sprout new plants from just small fragments containing as few as two whorls of leaves. That makes it very easy to spread. Hydrilla also prodcues turions and tubers in the soil, which can give rise to new plants after extended dormancy. In fact, one square foot plot of hydrilla can produce over 1,500 new plants!
Hydrilla is now listed by scientists as a federally noxious weed. One scientist compared it to herpes. “Once you’ve got it, you’ve got it forever.” Read more about Hydrilla.
3. A Carnivorous Flytrap.
The Venus Flytrap is native to a small region around Willmington, NC. Here, on the forest floor in the sandy soils of the pine forests, these small flytraps thrive in an area poor in nitrogen. To supplement their nutrient needs, they take insects. This helps put them ahead of the competition.
4. The Largest Single Flowering Infloresence
The Titan Arum boats the largest single, unbranched infloresence. The largest flower goes to Rafflesia, and the largest infloresence actually goes to the Tallabot Palm. But, this plant takes the prize for more than it’s size! It stinks! It’s often been called the Corpse flower, a name that doesn’t sound nearly as regal as the Titan Arum. Check out the Titan arum article we did on it after visiting a flowering one!
5. A Pot of Death
Pitcher plants grow all over the world in nitrogen rich soils. Would you be surprised to learn that they also share the habitat of the Venus fly traps? They’ve taken a different approach though. You see, they’ve actually formed into a vase, full of water to help drown their victims. While there are lots of Pitcher plants, and all of them seem to do this task slightly differently, they do share something in common. They all use animal protein to help give them an edge in their nutrient deficient habitats.
6. Corn and Vampires
You might not realize it, but if you eat a diet of nothing but corn, you may just become a vampire. Check out the video we did on it.
7. Kudzu
The Centennial Exposition, held in 1876 in Philadelphia, was a carnival of wonders. Roughly ten million Americans were introduced to the telephone, the typewriter, and a miraculous new plant from Japan: Kudzu.
Plant enthusiasts loved the flowers fruity, grapelike fragrance and the fact that the vine could scramble over a trellis so quickly and control erosion. Soon farmers realized that livestock would eat the vine, making it a good crop to feed livestock, but kudzu had other wicked plans for America. The vines made themselves at home, growing up to a foot per day during the warm summers. Over two-dozen stems can emerge from a single crown, and each of those can stretch for over one hundred feet. A single massive taproot can weigh up to four hundred pounds. Its underground rhizomes ignore the cold and survive for years before sprouting. It strangles trees, smothers meadows, undermines buildings and pulls down power lines. The vine now covers seven million acres in the US, and the damage it has caused is in the hundreds of millions. If you live in the south, you might not want to sleep with the windows open.
8. Purple Loosestrife
Do not be fooled by the stately, floral spires of purple loosestrife. This insidious weed grows from 3 feet to a towering 7 feet tall. Loosestrife takes over swiftly – a few plants dropping up to 2 million seeds per year – building a seed bank that can lay in the ground for years like a weedy trojan horse. If you drown it, the seeds can still live up to 20 months under water. Cut it up? Loose or trampled stems can produce roots and shoots, multiplying the problem. Try decreasing its light supply? Loosestrife will produce a different leaf morphology to adjust. With all these strategies in place, purple loosestrife can devastate native vegetation – overrunning thousands of acres of wetland at a time.
9. A Floating Fern – Salvinia
This free-floating aquatic fern introduced from an unregulated aquarium trade, can unbelievably double its population every two days! It forms dense mats up to three feet deep on the water’s surface. One of the largest infestations was a stunning ninety-six square miles of water surface. Giant salvinia is found in freshwater lakes, wetlands, and streams though out the southwestern US. It thrives in nutrient-rich water, so it grows particularly vigorously in water enriched by fertilizer run-off or sewer-treated plant waste. Just a tiny fragment chopped up by a boat propeller and stuck to the bottom of a vessel can spawn a who new colony in another water body. Once spread into a new lake it will take over until it has removed all of the oxygen from the water. Over 150 lakes in the US are battling Salvinia from Virginia to California.
10. Water Hyacinth – A showy floating plant.
This South American native aquatic plant is not hard to recognize. It grows to about three feet tall and sports luscious lavender blooms with a distinctive yellow spot on just one of its six petals. Although it is beautiful, the crimes that this aquatic plant has committed are so great that it should be locked away forever – if only that worked. Water hyacinth forms dense, sprawling mats on the waters surface that even boats have a hard time penetrating. Those mats become islands of their own, providing the perfect environment for other semi-aquatic plants and grasses to sprout. It is freakishly prolific, doubling its population every two weeks. Because of that its gone on a crime spree in Asia, Australia, the Americans and other parts of Africa. This plant ranks as one of the world’s worst aquatic weeds.
Other Bizarre Plants from Amy Stewart’s Wicked Plants
We’ve been inspired by this elegantly written book, and the work we did on the videos for the exhibit that we wanted to create a short list of plants, many of which we’ve filmmed already, so that you can explore some of the other deadly plants in a vicarious way.
In the past several years it has become very popular for the very, very rich multi-billionaire types to be interested in space ventures. Most of this has centered around commercial flights (Richard Branson, Virgin Galactic, Space X) for the lowly millionaires to go to space, but now a company called Planetary Resources has found several billionaires of its own to get behind their current project – Asteroid Mining.
Here’s a short video about this new, exciting project.
Where Do Asteroids Come From?
In the same Big Bang event that created Earth, the asteroids were made – of essentially the same materials. So the company plans to (over the next several decades) figure out how they can take water and mine precious metals from the NEAs – near Earth asteroids. Most of the asteroids in our solar system are in the asteroid belt between Mars and Jupiter, but there are about 9,000 NEAs – 1,500 of those are considered good prospects for asteroid mining.
What Do They Want to Mine from Asteroids?
The main things Planetary Resources is looking for are water and platinum group metals.
Water
The water will be extracted and separated into hydrogen and oxygen (the main components of rocket fuel) to create what would eventually become little space gas stations. This would solve some huge problems – since
carrying heavy fuel from Earth’s surface is one of the issues holding back deeper human space exploration. The water could also be used for the astronauts themselves – you know, since humans need water to live and all.
Platinum Group Metals
The metals they are looking for are in the platinum group – including platinum, iridium, osmium, palladium, rhodium, ruthenium. These would be dug up and sent back to Earth for use in all kinds of things. Platinum is useful in making electronics, treating cancer, in pace makers, in making spark plugs, coating wind turbine blades, making expensive jewelry, and a myriad of other things. This would be great for us because the cost of electronics could potentially be so low that all kinds of technology would be available to a lot more people.
When will they be able to mine asteroids?
The predictions for how long it will take is at least 30 years. The reason it’s going to take this long to send spacecraft to prospect and eventually extract minerals from asteroids is because the technology for this does not exist right now. This, for me, is the most exciting part of the whole thing. Spin-off products will be sure to emerge from such a challenging pursuit, and the spin-offs from every other space venture have made all of our lives better and easier in some ways. I have no doubt it is possible. Human ingenuity has made totally automated robots that work on the bottom of the ocean (totally amazing), and this is really pretty similar to that.
Who is Planetary Resources?
On April 23rd, 2012, Planetary Resources announced their plans to mine asteroids. Who are these bold individuals, you ask? The usual – a small number of very, very rich entrepreneurs. If you don’t know their names, you know who they are anyway. There are more, but the main publicized backers are listed below.
James Cameron – Director of Avatar and Titanic. He will be an advisor to the company, since he is only worth a mere $700 million.
Larry Page – Co-founder and CEO of Google. He is a billionaire backer.
Ross Perot, Jr. – Son of Ross Perot, the former presidential candidate and electronics entrepreneur. He’s a billionaire backer.
Eric Schmidt – Executive chairman of Google. He’s a billionaire backer.
Charles Simonyi – The guy who made Microsoft Office. He is a space nut who has been to the International Space Station and up to space in Russian Soyuz spacecraft.
There are a lot of smarts in this group, and I can’t wait to see how this all plays out.
Visualize it Better…
Space.com opened this image up to us. We think it portrays the scenario pretty well
On a typically chilly day, a kayaking race begins every year on the first Saturday in November at high noon. Hundreds of fans come out to the race to watch what has been called the most extreme kayaking race in the world. We wanted to check it out for ourselves and see what all the hype was about.
We camped out the night before to get a good spot on the cliffs overlooking the gorilla, the largest, and craziest looking drop of the course. For 4 hours, we watched racers go by. While most took it cleanly, there were a few that couldn’t pull the boat around to hit the fall cleanly. Check out this video of some of the carnage at the Gorilla!
What it takes to win
Winning a race like this means you’re an awesome kayaker. Yet, more than that you need experience on this course. Almost every person who places in a race like this is from the area. Locals are at a clear advantage because they know what lines to run. It almost becomes muscle memory after awhile. The race is an extremely fast race though. The winning times are under 5 minutes. Here are this year’s results.
Where is the Green River
The green river is located just southeast of Asheville. The river is damn fed, so it runs a good portion of the year. In fact, because of this and some of the other local rivers, there are a ton of kayaking manufacturers in the area.
Why is it that some objects float and others don’t? The truth is, it’s because of buoyancy. Here is the second video in our “science of the Olympics” series.
What is Buoyancy?
In physics, buoyancy is described as a force exerted by a liquid, gas, or other fluid that opposes an object’s weight. For kayakers, we usually discuss buoyancy relative to a kayak sitting in the water. So to understand buoyant force, we decided to go to the US National Whitewater Facility in Charlotte, NC.
In flat water, a kayaker and his/her boat are being pulled downward via gravity, and a buoyant force is pushing upward.
In simple terms the buoyant force is equal to the weight of the water the kayaker displaces. That seems pretty simple right? A 50kg kayaker and boat would displace 50kg of water. A 80kg kayaker and boat would displace 80kg of water. That way the forces are always equal and the kayaker doesn’t go anywhere.
In the Olympics, slalom kayakers have to go around gates. To change direction quickly, a kayaker can use bouyancy. You see, when they spin around a corner, they whip around the stern of the kayak. The energy of the change in velocity drives the stern of the boat underwater. The force is big which drives it down. It keeps going until the bouyant force slows it down. There is much more water displaced than the kayaker weighs. Since the bouyant force is now much greater than that of gravity, it rockets the kayaker out of the water. Because of the shape of the boat they can direct the force in the direction they want to go instead of just up. Here is a picture of Pablo McCandless mid-turn.
Maybe an easier way to look at this is with a trick kayak. Here Sam Fulbright balances the kayak on its nose. Notice how unequal the forces are at the bottom of his bounce (see picture below). Eventually it gets so great the kayaker can do a flip. How awesome is that!
Buoyancy Math Problem
Here is a fun little problem for you. Just as we highlighted at the end of the video, how would you calculate the force needed to sink the raft given the following…
Learn more about Olympic Slalom Kayaking / Canoeing
San Pedro Cactus
