Cast: Five 2 Nine Productions
Friday, December 31, 2010
Air Nautique Wake Games 2010: Opening Rounds
Air Nautique Wake Games 2010: Opening Rounds
With quick and substantial eliminations in each heat, only the cream of the crop will advance on to the next rounds of the 2010 Air Nautique Wake Games.Source: NEWS/Wakeboarding/Air_Nautique_Wake_Games_2010_Opening_Rounds_Results_0675.htm
Ashley Battersby And JF Houle Win The European Freeski Open 2010
Ashley Battersby And JF Houle Win The European Freeski Open 2010
Despite the terrible weather conditions, the event organizers of the 2010 European Freeski Open avoided disappointment by putting on a Stair Rail Battle. Ashley Battersby and JF Houle are the winners of the impromptu competition.Source: NEWS/Freeskiing/Ashley_Battersby_And_JF_Houle_Win_The_European_Freeski_Open_2010_0612.htm
Kiteboarding - Jurgen 01
TexasEagle posted a photo:
Kiteboarding on Grapevine Lake October 13, 2010. Large Size
Thursday, December 30, 2010
Wild New Route Planned For Absa Cape Epic 2011 MTB Race
Wild New Route Planned For Absa Cape Epic 2011 MTB Race
The Absa Cape Epic is the most prestigious mountain bike race in the world and 1,200 cyclists are expected to participate in the raw, natural locations of Saronsberg (Tulbagh), Worcester, and Oak Valley.Source: NEWS/Biking/Absa_Cape_Epic_2011_Mountain_Bike_Race_Africa_Preview_0803.htm
The Eerie Splendor Of Devils Tower
Article on guided crack-climbing journey up face of Devils Tower in Devils Tower National Monument in Wyoming; photos; maps
ASA BMX Triples 2010 At Bryce Jordan Center In Pennsylvania
ASA BMX Triples 2010 At Bryce Jordan Center In Pennsylvania
October may seem like it is far off in the distance, but now is the time to think about the 2010 BMX Triples event on October 23. Tickets are now on sale for the BMX contest at the Bryce Jordan Center in Pennsylvania.Source: NEWS/Biking/ASA_BMX_Triples_2010_Bryce_Jordan_Pennsylvania_Preview_0731.htm
Subaru Freeskiing World Tour 2010 Comes To A Close
Subaru Freeskiing World Tour 2010 Comes To A Close
Sadly, the 2010 Subaru Freeskiing World Tour has come to an end. The event was a blast for skiers and fans alike and the awe-inspiring demonstration of talent leaves everyone thirsting for more.Source: NEWS/Freeskiing/Subaru_Freeskiing_World_Tour_Comes_To_A_Close_Results_0622.htm
Record Number Of Teams Registered For Abu Dhabi Adventure Challenge 2010
Record Number Of Teams Registered For Abu Dhabi Adventure Challenge 2010
Since its inception in 2007, the Abu Dhabi Adventure Challenge has built on previous accomplishments, bringing ever-increasing numbers to its ranks further cementing its position as the world�s premier adventure race.Source: NEWS/Extreme_Sports/Abu_Dhabi_Adventure_Challenge_2010_Preview_0778.htm
The North Face Chilean Freeskiing Championships: McMillan and Stoeklein Win
The North Face Chilean Freeskiing Championships: McMillan and Stoeklein Win
McMillan and Stoeklein win The North Face Chilean Freeskiing Championships in El Colorado on the legendary Max�s Face. Stop #1 of the Subaru Freeskiing World Tour brought skiers from 11 countries to the heart of the Andes.Source: NEWS/Freeskiing/The_North_Face_Chilean_Freeskiing_Championships_Results_0759.htm
The Wheel Deal Part 1: Wheel Size
Many extreme sports rely on wheels of one type or another, including skateboarding, mountain boarding, inline skating, street luge, BMX and FMX. Different situations require different types of wheels, depending on the terrain and the types of riding you're doing.My favorite extreme sport is skateboarding, so this post focuses primarily on the options available in skate wheels. But the physics involved applies to any wheeled sport.
If you skate, you know that there are lots of wheels designs on the market from tiny, rock-hard wheels for street skating to giant, gummy wheels for old school cruising. Why are some wheels better for certain uses and not so good for others? As you probably guessed - it all comes down to physics.
Wheel Size
Among the many things you need to consider in choosing the best wheel for your riding is size. Most pro street skaters opt for small wheels. It's a good choice. Small wheels are fast on smooth surfaces such as skate park concrete, wood ramps, and most of the boxes, benches and banks you're likely to hit. But on asphalt or chewed up concrete, little wheels are much slower than big wheels. Just about every skater has at one time or another had the unpleasant experience of running across a pebble or crack that stops their board dead in it's path, sending the rider for a rough tumble. Those sorts of sudden stops are more likely if you ride tiny wheels.
So, what's size got to do with it? Well, here's a little sketch to show you what's going on.
The small red cirle represents a wheel with a diameter of about 50 millimeters, typical of lots of street and park wheels. The big black circle is like a large (95 millimeter) cruising wheel. This sketch shows the wheels just as they hit the edge of a 20 millimeter step (in this picture, I'm imagining the wheels rolling to the right), which is the sort of thing you might run across as you ride over the joints between sections of a typical sidewalk.The arrows show the direction of the force that results from the wheels hitting the obstacle. As you can see, the black arrow points up and to the left. That means some of the force pushes the wheel upward and some of it pushes back.
The red arrow is mostly pointed to the left and just a bit up, which means most of the force exerted by hitting the step goes into slowing the wheel, and the board it's attached to.
Of course, most of the bumps and cracks you'll run across in real life are a lot smaller than this. Even for smaller obstacles, though, more force will go into slowing a small wheel down than would go into slowing a larger wheel. You'll still get a force pushing the larger wheel upward, which makes for a rough ride, but at least it doesn't do as much to sap your speed (or stop you in your tracks).
If you race down a big hill made of asphalt, you end running over lots of little bumps that seriously slow small wheels, but aren't such a problem for big ones.
Are big wheels always better than small ones? Not at all. In fact, small wheels are usually MUCH faster than large wheels on smooth surfaces. Want to know why? Check out The Wheel Deal Part 2 in my next post to find out one reason that small wheels are better (sometimes).
Source: http://feedproxy.google.com/~r/blogspot/uUCU/~3/WRmZPn7vfuU/wheel-deal-part-1-wheel-size.html
Wednesday, December 29, 2010
Kiteboarding - Jurgen 01
TexasEagle posted a photo:
Kiteboarding on Grapevine Lake October 13, 2010. Large Size
Winners Of The Subaru North American Freeskiing Championships 2010
Winners Of The Subaru North American Freeskiing Championships 2010
The masters of the dangerous Cirque and winners of the 2010 Subaru North American Freeskiing Championship for the men's and women's divisions are Dylan Crossman and Janina Kuzma.Source: NEWS/Freeskiing/Subaru_North_American_Freeskiing_Championships_2010_Results_0610.htm
John Starr Jonathan Bergeron Jose Felix Hormaetxe Josh Clark
Blackpool Wake Park Opens In England
Blackpool Wake Park Opens In England
The impressive Blackpool Wake Park in Northern England is now under construction and the last details are almost finished for the grand opening, which is just in a matter of days.Source: NEWS/Wakeboarding/Blackpool_Wake_Park_Opens_England_2010_0687.htm
2011 iXS European Championships In Zermatt, Switzerland
2011 iXS European Championships In Zermatt, Switzerland
Zermatt, Switzerland has been chosen as the venue for the first year of the iXS European Championships. The event is scheduled for August 27th and 28th, 2011.Source: NEWS/Biking/XS_European_Championships_2011_Zermatt_Preview_0813.htm
iXS European Downhill Cup 2010: Julien Camellini Dominates In Pila, Italy
iXS European Downhill Cup 2010: Julien Camellini Dominates In Pila, Italy
One of the most beautiful races of the European series was staged last weekend in Pila. The cup�s penultimate race attracted 320 riders from 15 countries.Source: NEWS/Biking/iXS_European_Downhill_Cup_Pila_Italy_2010_Results_0760.htm
Tuesday, December 28, 2010
Kiteboarding - Roberto 01
TexasEagle posted a photo:
Kiteboarding on Grapevine Lake December 11, 2010. Large Size
Projekt Kackar Trailer
Mission to Turkey was really a blast!Movie, which we created is being a part of the Expedition Camera film festival. This is just a teaser!
For more detail information, please follow to expedicnikamera.cz (only in Czech language).
Cast: ROCKS & WATER production
Saturday, December 25, 2010
Indian Rock Park
This rugged 1.18 acre park, three blocks above the commerce of Solano Avenue, serves both relaxed visitors and serious mountain climbers.Source: http://www.nytimes.com/2010/09/12/us/12bcintel.html?partner=rssnyt&emc=rss
Friday, December 24, 2010
For Rock-Climbing Guru, the Sky Is His Roof
Charles Victor Tucker III, the harmless and stoned jester of the mountains to some and the scourge of Yosemite National Park to others, is better known as Chongo, a rock climber who wrote books on physics and now sleeps under a tractor-trailer.Source: http://www.nytimes.com/2008/09/30/sports/othersports/30chongo.html?partner=rssnyt&emc=rss
Nine Knights 2010: The Knights Are Ready
Nine Knights 2010: The Knights Are Ready
The line up for the most exciting freeski event of the year is set. The Nine Knights is anything but the usual freeski competition and on the 24th of April they will leap through the snow, battling for fame and glory.
Skate Science
Click the picture to see a little video about skateboarding science that I helped my friends at the American Institute of Physics put together. It's part of the Discoveries and Breakthroughs Inside Science program. I play the skateboarding physicist.
The still shot you see here has nothing to do with the actual video, except that it's a picture of me on a skate ramp.
In
-Buzz
Source: http://feedproxy.google.com/~r/blogspot/uUCU/~3/_GIojlV-WUE/skate-science.html
Thursday, December 23, 2010
Getting Exercise on St. Thomas (Bird?s-Eye Views Are a Bonus)
If you?re looking for something more thrilling than lying on the beach, perhaps you should try the island?s newest activity: rock climbing.
Source: http://travel.nytimes.com/2008/11/09/travel/09COMrock.html?partner=rssnyt&emc=rss
Major Upsets Expected At the 2010 Horsefeathers Pleasure Jam
Major Upsets Expected At the 2010 Horsefeathers Pleasure Jam
It's that time of the year and the snowboarding community is making its way back to the Northern Hemisphere for the 2010 Horsefeathers Pleasure Jam.Source: NEWS/Snowboarding/4Star_Horsefeathers_Pleasure_Jam_2010_Austria_Preview_0806.htm
Gary Stelfox and Tor Young crowned King and Queen of Cable 2009
Gary Stelfox and Tor Young crowned King and Queen of Cable 2009
Nick Davies, Sophie Cordery, Bret Little, Szebastian Szolath and Andreas Voss earn titles at the final stop of the 2009 WWA Europe Wake Park Series (EWPS) at Princes Club, London.Source: NEWS/Wakeboarding/King_of_Cable_2009_London_0503.htm
Ready to Climb the Walls? Here?s a Better Alternative
A rock-climbing adventure in the White Mountains of New Hampshire provides thrilling views and a break from sibling squabbles.Source: http://travel.nytimes.com/2009/09/18/travel/escapes/18climb.html?partner=rssnyt&emc=rss
Mastercraft Pro Wakeboard Tour 2010 Fantasy Game
Mastercraft Pro Wakeboard Tour 2010 Fantasy Game
$2,000 in prize money will be up for grabs this year in the 2010 MasterCraft Pro Wakeboard Tour fantasy game. Earn points for your fantasy team as the pro riders compete on tour.Source: NEWS/Wakeboarding/Mastercraft_Pro_Wakeboard_Tour_2010_Orlando_Preview_0684.htm
Elias Amb�hl Rocks The Fridge Festival Big Air In Budapest
Elias Amb�hl Rocks The Fridge Festival Big Air In Budapest
Budapest hosted the first ever major freeski event in Eastern Europe with the Fridge Festival last weekend. This event is an exciting preview of the superior freeskiing that the upcoming winter season has in store.Source: NEWS/Freeskiing/Fridge_Festival_Big_Air_2010_Budapest_Results_0809.htm
The Wheel Deal Part 2: Wheel Size (again)
Bigger wheels are faster on rough surfaces, as I pointed out in my last post, because more of the forces that they experience as they roll over bumps pushes the wheel up rather than pushing backwards and slowing the wheel and rider down.So, why not just ride the largest wheels you can find? Unfortunately, when it comes to skateboarding and inline skating, larger wheels simply don't roll as well on smooth surfaces. The problem is that the urethane they're made of changes shape when you ride.
A simplified model of a skate wheel might look like this, where the jagged lines are meant to be springs that represent the compressible urethane. That's not to say that there are actual springs inside the wheels. It's just that the urethane acts much like springs, and it's simpler to understand the way wheels work if you pretend that they're are made of springs.As you can see in this sketch (I've exaggerated things a lot to make it easier to visualize), a wheel deforms as you ride along, resulting in a flat spot where the wheel touches the ground.
Most skate wheels are solid cylinders of material, except for the hole running through the middle where the bearings sit and the axle passes through. The springy urethane compresses when your weight pushes down on it. If you look at two wheels that are identical in shape except that one is large and the other is small, and both are made of exactly the same urethane, the larger wheel will deform more under the same weight.
This is where we can use physics to understand what's going on a little more precisely. Physicists think about springs in terms of something called the spring constant (usually symbolized with the letter k). The higher the spring constant, the more force you need to stretch or compress the spring.
If you connect two springs end to end, the total spring constant goes down (from k to k/2). In other words, it will be easier to stretch two springs connected in a row than it is to stretch just one. (You can test this yourself by tying rubber bands end to end.)As you can see in this sketch, attaching two springs side by side increases the total spring constant (from k to 2k), making them harder to stretch.If you cut a spring in half, it will double the spring constant. It's like taking the two springs connected end-to-end and getting rid of one, which doubles the spring constant from k/2 to k.
This is relevant to skate wheels because you could always make a small wheel by shaving down a big wheel. If you were to do that with the model of a wheel that I drew above, you're essentially shortening the springs. This makes the wheel stiffer (which is to say, less springy). Your weight pressing down on a small wheel will not deform the wheel as much because it's effective spring constant is much higher than it would be for a wheel that's identical in very way except for its larger size.
This makes larger wheels slower because compressing and stretching springs, or springy urethane, takes energy. With a perfect spring, you get all the energy back as it springs back to its natural shape. But no springs are perfect, and urethane is usually far from perfect.
Urethane is fairly resilient, which means that once it's deformed it bounces back into shape and gives back some of the energy that deformed it, just like stretching and releasing a spring. Depending on the exact formula of the urethane, a portion of the energy is always lost. Most of the lost energy turns into heat that warms the wheel and escapes into the air. If you squish a skate wheel you can expect to get back no more than 75% of the energy you put into it, and usually you get back a lot less. As a rough estimate, the deformation that comes with rolling on a urethane wheel will cause a large wheel to lose twice as much energy as one half its size. That's what makes larger wheels slower.
There are several ways to reduce the amount of energy lost due to the squishing of skate wheels. One common solution is to replace some of the urethane with a rigid core, like this Spitfire wheel.
Another possibility is to make the wheels wider, like these old school wheels.
Take a look at the cutaway sketch below that shows why wider wheels are less squishy. By widening the wheels, you're adding more springs (well, springy urethane anyway) in parallel. If you recall the diagram above, adding more springs side-by-side increases the total spring constant and makes it harder to stretch or compress the springs.
The wheel on the right is three times wider, and should be three times more rigid than the wheel on the left.
So, if you want bigger wheels that will roll as fast as smaller wheels, you have to make them wider. That leads to other problems. For one thing, wheels that are wide and have big diameters are heavy. That's not so good for all the ollie-based street moves, but fine for ramp, bowl and downhill skaters.
Another problem, which can be bad for all sorts of situations, is that the wider you make a wheel the harder it is to corner. If you try to ride in a circle, the outer edge of the wheel travels farther than the inner edge. Because both parts have to roll at the same speed, either the outer part of the wheel ends up turning too slowly or the inner part turns to quickly. That can lead to lots of wear and tear on the wheels, as well as extra friction that will slow you down whenever you change direction.
I've already explained why you need large wheels for riding on rough surfaces. Now you can see why smaller wheels are better for skating park concrete and obstacles. So, why not get REALLY tiny wheels for skating on smooth surfaces? Unfortunately, when wheels get too small other problems start to crop up. This post is already long enough, so I'll tell you about those issues some other time.
Source: http://feedproxy.google.com/~r/blogspot/uUCU/~3/OYiWOAttVFs/wheel-deal-part-2-wheel-size-again.html
Wednesday, December 22, 2010
Air And Style Beijing 2010: First Ever Snowboard Event In China!
Air And Style Beijing 2010: First Ever Snowboard Event In China!
Riders from around the world will make the trek to China for the Air & Style Beijing and, in addition to getting ready for the first major event of the TTR season, will be treated to a cultural experience that will be unmatched at any other tour stop this year.Source: NEWS/Snowboarding/TTR_Tour_6Star_Air_And_Style_Beijing_2010_Preview_0811.htm
John Starr Jonathan Bergeron Jose Felix Hormaetxe Josh Clark
Tom Carroll - The Snap -Forerunners 2
Tom Carroll, of Newport NSW, is one of the most powerful surfers of all time. This two-time world champion's contributions to the sport, his competitive spirit and his memorable waves at Pipeline, have made his career legendary.
Anatomy of a Monster Aerial
When snowboarding's living legend Terje Haakonsen launched off of the big quarterpipe at The Arctic Challenge last March, he sailed 9.8 mind-blowing meters (32 feet) in the air. He set the world record for big air on a snowboard and gave us some wicked footage to boot. Transworld's video is my favorite clip of Terje's air, but the YouTube video below is pretty entertaining too.
I thought it might be interesting to run some of the numbers to see what sort of physics was involved when Terje shattered the record. Here's what I've come up with so far . . .
-Terje's top speed as he approached the bottom of the giant quarterpipe was at least 70.92 kilometers per hour (44.1 mph).
-The g-forces he experienced as he rode up the ramp peaked out at around 4 to 5 times the force of gravity, which means his legs were briefly supporting the equivalent of about 337 kilograms (743 pounds) or more.
-Terje's trip above the top of the ramp lasted just about 2.8 seconds, although I'm sure it seemed a lot longer to him.
-As you may recall from my post about the FMX backflip limit, it takes energy to rotate as well as catch air. Terje set the record with a massive 360 aerial. If he hadn't been spinning he could have gone just a little higher. But it turns out that doing an air-to-fakie instead of a 360 would have only boosted him another centimeter or so. It looks like the Arctic Challenge judges couldn't have measured such a slight difference, so he still would have ended up with the same 9.8 meter record.
What if Terje had approached the hill at world record downhill snowboarding speeds instead?
-At an approach speed of 201 kilometers per hour (124 mph), the current world record for snowboarding, Terje would have sailed about 79 meters (259 feet)in the air.
-He would have experienced a crushing g-force 32 times gravity, the equivalent of about 2400 kilograms (5291 pounds), as he rode up the ramp.
-His total hang time would have been about 8 seconds.
In case you want to check the numbers yourself, I've listed the equations and other information I used to make these estimates below.
The Mathy Bits
Some of the things you need to know to analyze Terje's monster air are
Terje's mass - roughly 75 kilograms
The radius of the Arctic Challenge quarterpipe's transition - about 10 meters
Terje's moment of inertia when he reaches down to grab the board is about 5 kilogram meters^2. (I got that number from page 313 of a book called "The Physics of Sports", edited by Angelo Armenti, Jr.)
The equation for gravitational potential energy, E = m g h
where,
E = energy
m = mass
h = height
The kinetic energy equation, E = (1/2) m v^2
where v is velocity, and v^2 means velocity squared
The centripetal force equation F = (m v^2)/r
where r is the radius of the quarterpipe's transition.
The equation for motion of an object under constant acceleration x = x0 + v0 t + (1/2)g t^2
where g is the acceleration due to gravity
t is time and t^2 is time squared
The equation for rotational energy is E = (1/2) I w^2
where I is moment of inertia
w is angular velocity
I thought it might be interesting to run some of the numbers to see what sort of physics was involved when Terje shattered the record. Here's what I've come up with so far . . .
-Terje's top speed as he approached the bottom of the giant quarterpipe was at least 70.92 kilometers per hour (44.1 mph).
-The g-forces he experienced as he rode up the ramp peaked out at around 4 to 5 times the force of gravity, which means his legs were briefly supporting the equivalent of about 337 kilograms (743 pounds) or more.
-Terje's trip above the top of the ramp lasted just about 2.8 seconds, although I'm sure it seemed a lot longer to him.
-As you may recall from my post about the FMX backflip limit, it takes energy to rotate as well as catch air. Terje set the record with a massive 360 aerial. If he hadn't been spinning he could have gone just a little higher. But it turns out that doing an air-to-fakie instead of a 360 would have only boosted him another centimeter or so. It looks like the Arctic Challenge judges couldn't have measured such a slight difference, so he still would have ended up with the same 9.8 meter record.
What if Terje had approached the hill at world record downhill snowboarding speeds instead?
-At an approach speed of 201 kilometers per hour (124 mph), the current world record for snowboarding, Terje would have sailed about 79 meters (259 feet)in the air.
-He would have experienced a crushing g-force 32 times gravity, the equivalent of about 2400 kilograms (5291 pounds), as he rode up the ramp.
-His total hang time would have been about 8 seconds.
In case you want to check the numbers yourself, I've listed the equations and other information I used to make these estimates below.
The Mathy Bits
Some of the things you need to know to analyze Terje's monster air are
Terje's mass - roughly 75 kilograms
The radius of the Arctic Challenge quarterpipe's transition - about 10 meters
Terje's moment of inertia when he reaches down to grab the board is about 5 kilogram meters^2. (I got that number from page 313 of a book called "The Physics of Sports", edited by Angelo Armenti, Jr.)
The equation for gravitational potential energy, E = m g h
where,
E = energy
m = mass
h = height
The kinetic energy equation, E = (1/2) m v^2
where v is velocity, and v^2 means velocity squared
The centripetal force equation F = (m v^2)/r
where r is the radius of the quarterpipe's transition.
The equation for motion of an object under constant acceleration x = x0 + v0 t + (1/2)g t^2
where g is the acceleration due to gravity
t is time and t^2 is time squared
The equation for rotational energy is E = (1/2) I w^2
where I is moment of inertia
w is angular velocity
Source: http://feedproxy.google.com/~r/blogspot/uUCU/~3/oB7RQ3yrd-Y/anatomy-of-monster-aerial.html
Indian Rock Park
This rugged 1.18 acre park, three blocks above the commerce of Solano Avenue, serves both relaxed visitors and serious mountain climbers.Source: http://www.nytimes.com/2010/09/12/us/12bcintel.html?partner=rssnyt&emc=rss
Freestyle Motocross Backflip Limit
Freestyle Motocross superstar Travis Pastrana hails from Annapolis, MD. That's just down the road from my home town. Besides the fact that FMX is simply cool, having one of the most famous competitors based so nearby means that my son can't help but love watching the competitions (OK, I'll admit it, I like them too).
One day as we were watching Travis throw down backflips and double backflips on Fuel TV, it made me wonder just how many flips were at least theoretically possible. Well I finally got around to doing the calculations.
I'm not going to keep you in suspense - according to my caculations (I love saying that) the most backflips that a person could possibly do on an FMX bike seems to be 4.
This may be hard to believe, considering that nobody has managed more than a double backflip yet. In case you're wondering how I figured it out, read on for a brief sketch. If you don't really care about the physics, you can still rest assured that FMX has some room to progress, at least in the backflip department.
FMX Backflip Calculation
The first thing to consider in calculating the maximum number of backflips in FMX is that there is a limited amount of energy available. You can estimate the maximum amount of energy from the record FMX step up height (the equivalent of high jumping on FMX bikes), which currently stands at about 11 meters.
The energy necessary to lift a bike and rider 11 meters off the ground is
E=m g h= 16500 joules
where m is the total mass of the bike plus rider, which I estimated to be 150 kilograms
g is the acceleration of gravity, or 9.8 meters per second squared
and h is the height
When a rider flips, some of the energy that they would have used to achieve height is put instead into the energy of their rotation. Optimally, the energy should be split equally between the upward motion and the rotation. I can prove this, but it requires a little bit of calculus, which is hard to show in the rudimentary editor that Blogger provides. But it seems pretty sensible, if you think about it.
If anyone wants to know the details, drop me an email and I'll explain it. For now, you'll have to take it on faith.
Once you know the amount of energy that goes into getting altitude (16500/2 joules), you can figure out how high they fly during a max backflip attempt and how long they are in the air during a jump. Because they?re diverting half the total energy into spinning, and half of the total energy to getting height, they should only travel about half as high as in a record setting step up competition, or 5.5 meters (18 feet) off the ground.
To figure out how long the whole trip takes, you have to use the equation
h=1/2(g * t^2)
where ^2 means time (t) is squared.
This is the equation for how far something would travel (h) under constant acceleration (in this case, the acceleration due to gravity g) in a certain amount of time (t).
Because we know h and g, but not t, you have to rearrange this equation to find out how long it takes to go from the ground to a height h.
t=(2*h/g)^1/2
(^1/2 means the square root of (2*h/g))
But don't forget that the rider has to come back down as well, so the round trip is twice as long as it takes to get to h.
You can also calculate how fast they are rotating by using the equation for rotational energy.
E=1/2(I * w^2)
Where E again is 16500/2 joules, I is the rotational moment of intertia, and w is the rotational speed.
A little mathematical manipulation leads to the equation
total rotations (in radians) = w*t =(v^2/g)(m/I)^1/2
I also guessed that the bike and rider's rotational inertia (I) is about 150 kilogram meters squared. It's a reasonable estimate, and I can explain it to the very curious folks, but it doesn't make much difference in the final calculation (because we're taking the square root of I).
If you plug in the numbers, you find that an FMX rider could theoretically rotate through no more than about 22 radians. Radians are the measure of rotation in the units I'm using (SI).
There are 2*pi radians in a circle, so in other words they will do 3.5 full rotations, which corresponds to a quad backflip.
Here's how 3.5 rotations equals 4 flips in FMX.
In performing a single flip - the rider leaves the hill with their front tire pointing toward the sky and comes down with it pointed to the ground. Here's a video to prove it
That means the bike and rider actually rotate only a little more than halfway around when doing a single backflip. For every additional backflip, they add another full rotation. So, 3.5 rotations is the same as a quad-backflip.
There you have it. Based on data from the record setting step up competition, we can expect, someday, to see a very daring and talented FMX rider to pull of a quad backflip, but never any more (unless they try it on a much more powerful bike).
One day as we were watching Travis throw down backflips and double backflips on Fuel TV, it made me wonder just how many flips were at least theoretically possible. Well I finally got around to doing the calculations.
I'm not going to keep you in suspense - according to my caculations (I love saying that) the most backflips that a person could possibly do on an FMX bike seems to be 4.
This may be hard to believe, considering that nobody has managed more than a double backflip yet. In case you're wondering how I figured it out, read on for a brief sketch. If you don't really care about the physics, you can still rest assured that FMX has some room to progress, at least in the backflip department.
FMX Backflip Calculation
The first thing to consider in calculating the maximum number of backflips in FMX is that there is a limited amount of energy available. You can estimate the maximum amount of energy from the record FMX step up height (the equivalent of high jumping on FMX bikes), which currently stands at about 11 meters.
The energy necessary to lift a bike and rider 11 meters off the ground is
E=m g h= 16500 joules
where m is the total mass of the bike plus rider, which I estimated to be 150 kilograms
g is the acceleration of gravity, or 9.8 meters per second squared
and h is the height
When a rider flips, some of the energy that they would have used to achieve height is put instead into the energy of their rotation. Optimally, the energy should be split equally between the upward motion and the rotation. I can prove this, but it requires a little bit of calculus, which is hard to show in the rudimentary editor that Blogger provides. But it seems pretty sensible, if you think about it.
If anyone wants to know the details, drop me an email and I'll explain it. For now, you'll have to take it on faith.
Once you know the amount of energy that goes into getting altitude (16500/2 joules), you can figure out how high they fly during a max backflip attempt and how long they are in the air during a jump. Because they?re diverting half the total energy into spinning, and half of the total energy to getting height, they should only travel about half as high as in a record setting step up competition, or 5.5 meters (18 feet) off the ground.
To figure out how long the whole trip takes, you have to use the equation
h=1/2(g * t^2)
where ^2 means time (t) is squared.
This is the equation for how far something would travel (h) under constant acceleration (in this case, the acceleration due to gravity g) in a certain amount of time (t).
Because we know h and g, but not t, you have to rearrange this equation to find out how long it takes to go from the ground to a height h.
t=(2*h/g)^1/2
(^1/2 means the square root of (2*h/g))
But don't forget that the rider has to come back down as well, so the round trip is twice as long as it takes to get to h.
You can also calculate how fast they are rotating by using the equation for rotational energy.
E=1/2(I * w^2)
Where E again is 16500/2 joules, I is the rotational moment of intertia, and w is the rotational speed.
A little mathematical manipulation leads to the equation
total rotations (in radians) = w*t =(v^2/g)(m/I)^1/2
I also guessed that the bike and rider's rotational inertia (I) is about 150 kilogram meters squared. It's a reasonable estimate, and I can explain it to the very curious folks, but it doesn't make much difference in the final calculation (because we're taking the square root of I).
If you plug in the numbers, you find that an FMX rider could theoretically rotate through no more than about 22 radians. Radians are the measure of rotation in the units I'm using (SI).
There are 2*pi radians in a circle, so in other words they will do 3.5 full rotations, which corresponds to a quad backflip.
Here's how 3.5 rotations equals 4 flips in FMX.
In performing a single flip - the rider leaves the hill with their front tire pointing toward the sky and comes down with it pointed to the ground. Here's a video to prove it
That means the bike and rider actually rotate only a little more than halfway around when doing a single backflip. For every additional backflip, they add another full rotation. So, 3.5 rotations is the same as a quad-backflip.
There you have it. Based on data from the record setting step up competition, we can expect, someday, to see a very daring and talented FMX rider to pull of a quad backflip, but never any more (unless they try it on a much more powerful bike).
Source: http://feedproxy.google.com/~r/blogspot/uUCU/~3/oUYtQbaEZm0/fmx-backflips-limit-14.html
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