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Go Back   WakeWorld > >> Wakeboarding Discussion Archives > Archive through November 16, 2009

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Old     (dooie)      Join Date: Feb 2007       11-01-2009, 10:03 PM Reply   
G'day,i often wonder how fast my head is traveling when i catch a front edge.
thought some of you might know.

you'll have to take into count the boat speed, the speed when you jump the wake and that the top part of the body is traveling faster than the bottom.

i hope you can help me out cheers
Old     (lives2wake)      Join Date: Apr 2002       11-02-2009, 5:43 AM Reply   
LOL...I'd like to see the math behind this too.
Old     (gene3x)      Join Date: Apr 2005 Location: Dallas , TX       11-02-2009, 8:02 AM Reply   
I would say at least twice as fast as your speed, but it depends on if your head gets whipped. That is how a pitcher gets his speed on the ball is by creating that whip effect through his body.
Old     (fullonsalesgrp)      Join Date: Jan 2004       11-02-2009, 8:51 AM Reply   
http://dsc.discovery.com/tv/time-warp/time-warp.html

Write in they are already doing just a wakeboard episode
Old    mcbean7            11-02-2009, 10:13 AM Reply   
Since I do my fair share of faceplants, I'm interested to see the results also.
Old     (duffmangt)      Join Date: Jan 2008       11-02-2009, 10:29 AM Reply   
no way itch! thats awesome, any idea of when it will air??
Old     (duffmangt)      Join Date: Jan 2008       11-02-2009, 10:29 AM Reply   
i also think mythbusters should do the helmet myth ;)
Old     (rallyart)      Join Date: Nov 2006       11-02-2009, 10:32 AM Reply   
A 22 mph boat takes a wakeboarder faster than 40 mph going across the wake. Assuming your board stops instantly when an edge is caught and your head is still traveling at 40 you just pendulum around and strike the water at 40 mph.
Now your board does not usually stop instantly so it'll me a smidge lower.
Old     (bendow)      Join Date: Sep 2005       11-02-2009, 12:08 PM Reply   
I've taken some hard face plants. I'd say the impact on some of them have been Mach 3+
Old     (dirwoody)      Join Date: Apr 2003       11-02-2009, 12:32 PM Reply   
What about a Raley to face plant? I'd say at least 60MPH plus however quickly you're coming down
Old     (flattirenotube)      Join Date: May 2007       11-02-2009, 1:53 PM Reply   
Art,

Your head would be traveling much faster than your feet. The theory is based upon centripetal speed. Assuming that all parts of your body hit the water at the same time, or head first, the head has to spin faster to meet the water at same time. While you would be traveling at the same revolutions per minute (RPM), it is traveling a further distance in the same amount of time (MPH). Again this is basing it upon every point of your body being rigid and contacting the water at the same time. If your head hits before anything else it is traveling even faster. It is a physics theory that I don't have time to run calcs for right now, but you could try it pretty easy. Just consider your feet the center axis that everything is rotating around.

http://www.ajdesigner.com/phpcircularmotion/centripetal_acceleration_equation_velocity.php

Edited for Spelling.


(Message edited by flattirenotube on November 02, 2009)
Old     (ralph)      Join Date: Apr 2002       11-02-2009, 1:59 PM Reply   
The only way to know for sure is to strap a shadow box to your Mellon and go out and drill yourself. Make sure you take video and post it up.
Old     (nelsonwakeboarding)      Join Date: Mar 2008       11-02-2009, 2:14 PM Reply   
I've been wondering about this for the past two weeks, ever since I got knocked out and suffered a major concussion catching my toe side edge on a whirlybird. Is it worse if you also have the momentum of a spin? Surely it must be worse if you are going big, otherwise why would they say "The bigger they are, the harder they fall"...-Mrs. Nelson
Old     (wake77)      Join Date: Jan 2009       11-02-2009, 3:01 PM Reply   
"If your head hits before anything else it is traveling even faster. It is a physics theory that I don't have time to run calcs for right now, but you could try it pretty easy. Just consider your feet the center axis that everything is rotating around."

Real simple

a(sub c)= v^2/r (V represents velocity, r representing radius)

[Real world applications are tough, because this does not include friction (air resistance), and it is tough to know the velocity at the exact moment your edge catches and you are flung face first into the water.]
Old     (andrewjet)      Join Date: Jan 2003       11-02-2009, 3:25 PM Reply   
Boat 23? mph..board catches the edge and slows you down a bit..your head hits around 22-23 mph. That's a big damn hit. No calculator needed. LOL! Jet
Old     (amo)      Join Date: Jan 2009       11-02-2009, 5:48 PM Reply   
Darren^^^^^ LMAO!! I would pay to see that! That is funny just thinking about that scene.

Obviously crashing hard is not funny, but if you are going to do it on purpose...that's straight out of the movie Jacka$$ type stuff. That is funny.

(Message edited by amo on November 02, 2009)
Old     (ktm525)      Join Date: Mar 2009       11-02-2009, 6:40 PM Reply   
I think it should be filmed by Time Warp. Any volunteers?
Old     (dnp33)      Join Date: Jan 2007       11-02-2009, 8:58 PM Reply   
well assuming when you catch your edge the board stops (which is what it looks like when you watch a good edge catch in slow-mo) the best way to do the calculation using physics would be to take a video of the crash to find how long it takes from edge catch to face plant, multiply it by 4 to get a full period (one rotation ) and use that to find your angular velocity w (w=2pi rad/period) then w x your height = v and that should equal the speed of your head.

assuming you catch your edge after landing, not during which would be harder to calculate.
Old     (rallyart)      Join Date: Nov 2006       11-02-2009, 9:15 PM Reply   
Good point Patrick. Stop the bottom and the center of mass is still traveling 40. That's a little above the center of the body so the head would be doing significantly faster. Of course the board never just stops but I know I've washed the back of my eyeballs on faceplants and I'm not good enough to cross the wake at anywhere near 40. I like the helmet.
Old     (adambarry)      Join Date: Sep 2008       11-02-2009, 11:10 PM Reply   
I got tat im going 40 mph with my fall which sounds way intense. I got .4 seconds on my time for edge catch to face plant. And I got a concussion from that one... I'm six feet tall. and now im at a stand still on how to figure the rest out, im in trig too : /. Sorry if anyone said something that would solve that I didn't really read much of the previous posts....
Old     (lukus)      Join Date: Jul 2009       11-03-2009, 8:54 AM Reply   
Don't know that the calculation needs to be that complicated.....should just be distance traveled by head divided by time. The time is the critical factor because little changes will have a large effect on the result. Taking the example numbers from the previous post this is what I get:

distance traveled by head (6ft person): C/4(1/4 of circle)=pi x d/4 = pi x 2(6ft)/4=3pi ft
time to travel distance: .4s
Velocity = 3pi ft/.4 s = 7.5pi ft/s
Convert to mi/hr: V= 7.5pi ft/sx3600s/hrx1/5280 ft/mi = 16.1 mi/hr

say it took .3 seconds to faceplant instead of .4 s......V=22.4 mi/hr

.2s.....V=33.6 mi/hr
Old     (clay_fraley)      Join Date: Jul 2006       11-03-2009, 10:03 AM Reply   
hahaha i agree with benjamin on the mock 3+

I've been worked way to many times

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