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Physics and skiing

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Itsbackfliptime
Posts: 18901 - Karma: 75
Does anyone ever figure out how fast they need to go to clear jumps? With how huge jumps are nowadays you'd think that they'd spend an extra five minutes to figure how fast they need to go. Especially when they're towing in with snowmobiles and know how fast they're going.
Feb 1 2006 9:40AM
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Jwenz
Posts: 8893 - Karma: 7,634
well after i saw dumonts crash again today i really thought of something. We this year in math, kinda wierd learned this equation where you solved for either speed, or height, and in this case all you need is the length of the gap, and the andle, and time in air, to find speed but it is hard finding two variables, but i mean jeez this is crzy shit, 130 feet for chads gap coming up short WOULD FUCKING SUCK
Feb 1 2006 9:49AM
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freestyler540
Posts: 13106 - Karma: 18,907
I used the formula in high school physics.I cant remember it!!!
Feb 1 2006 10:06AM
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jibjim
Posts: 1814 - Karma: 10
well, if you know anything, you would have kept your notes, like this could have saved tanners injury and let him completely dominate the sport in everyway, not just somewhat dominate it
Feb 1 2006 10:11AM
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user098123
Posts: 6072 - Karma: 18
Not necessarily, for chads you aren't towed in by a snowmobile are you? I mean, I know for Dumont, he was, so it would help to know your speed there, but for Tanner that was all by how it felt.

You also have to think of this, it depends how they go off the lip. They could pop, or they could go off it switch or take off of it early or any number of factors, so yes, it would make it potentially easier to hit the landings, but there are many flaws in the equation.
Feb 1 2006 10:16AM
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newschooler7
Posts: 2253 - Karma: 21
yea there are a bunch of variables. it could help just to rough it though.
Feb 1 2006 10:20AM
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iamdan.
Posts: 1146 - Karma: 11
projectile motion would be the physics formulae you would have to use in order to calculate the distance and speed. but how the hell would you know how fast your going? you gonna get someone to gun you and let you know if your going fast enough...nah fuck that, its called rock paper scissors!
Feb 1 2006 10:23AM
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KRASHED
Posts: 7803 - Karma: 466
Also need to factor in the resistance of the snow, wether it be corn snow, packed snow or groomed powder they all have different resistance factors.
Feb 1 2006 10:29AM
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Jwenz
Posts: 8893 - Karma: 7,634
yeah you would have some one gun you for speed checks
Feb 1 2006 10:40AM
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Adamskinick
Posts: 3353 - Karma: 126
its one thing in a controlled experiment like an equation to determine how much a ball needs to roll off a block or something in class. but wind resistance, pop, weight displacement, friction, all more involved than a simple d=vi delta t bla bla bla..
Feb 1 2006 10:43AM
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Schoellkopf
Posts: 1300 - Karma: 122
speed check anyone?
Feb 1 2006 10:45AM
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Powdahound
Posts: 522 - Karma: 9
there would be a lot of variables but krashed, the type of snow that you were on would not matter.. only speed, height angle, distance.. which could all be done and then i have no clue how you would factor in popping or not at the lip
Feb 1 2006 10:52AM
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BChronic
Posts: 217 - Karma: 10
they had a gun there at one time i recall
Feb 1 2006 10:55AM
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Powdahound
Posts: 522 - Karma: 9
H(t)=-16t2+Vt+h is the formula for projectile motion... the function H(t) represents the height at any given time .. V is the inital velocity (or when you take off the jump)and then h is the height at take off .. so i guess you could try and factor in pop there... it would probably be most beneficial in a table so you could see at different speeds how the height vs. time changes
Feb 1 2006 10:57AM
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Powdahound
Posts: 522 - Karma: 9
the t2 is T squared i couldn't represent it on my keyboard sorry for the multiple posts
Feb 1 2006 10:58AM
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treesmann
Posts: 2675 - Karma: 49
im in ap physics and we have to do an end of year project because we finish the class middle of may. this is a perfect idea for my project
Feb 1 2006 10:59AM
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japie99
Posts: 2128 - Karma: 20
U can propably calculate it with W=fs W=0.5mv^2 Thing is u dont no really what F is.
Feb 1 2006 11:00AM
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PurpleSkier
Posts: 5634 - Karma: 311
Did you see TBC? they had a radar gun.
Feb 1 2006 11:00AM
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waterville_NH
Posts: 3411 - Karma: 23
exactly, and even if they gunned you, are they going to like wave their arms if you're going too fast or slow, the only way this would work is with the snowmobile tow in scenario
Feb 1 2006 11:02AM
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Powdahound
Posts: 522 - Karma: 9
yeah it would deffinitly be something sweet to look into.. if you do it let us know the end result
Feb 1 2006 11:02AM
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PurpleSkier
Posts: 5634 - Karma: 311
You speed check, you can clock how fast you're going, and then stop on the jump, side slip it. you guys must have never done aerials as a kid growing up
Feb 1 2006 11:05AM
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waterville_NH
Posts: 3411 - Karma: 23
can't say that i did
Feb 1 2006 11:13AM
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PurpleSkier
Posts: 5634 - Karma: 311
Then you know nothing of what you're talking about. Stop contributing useless shit.
Feb 1 2006 11:14AM
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Bepo
Posts: 8195 - Karma: 17
Yeah, same here man, I had the same kinda idea too. But you could find the necesary speed with simple projectile motion, but im not quite sure how to account for air resistance.

BTW, coeficient of kinetic friction for skis on snow is about .04 if anyone ever wants to know...
Feb 1 2006 11:17AM
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Itsbackfliptime
Posts: 18901 - Karma: 75
Theres some pretty easy equations for figuring out the velocity of something sliding down a hill too. You'd need the coefficient of friction and stuff too but you could figure that out with a stopwatch and someone sliding down the hill.
Feb 1 2006 11:29AM
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treesmann
Posts: 2675 - Karma: 49
cofficient for snow is given in the ref tables, but i would also have to do some stuff about sidecut and turning. idk, it would probably be complex.
Feb 2 2006 9:58AM
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GotamaBCshredder
Posts: 5062 - Karma: 424
I don't get it, I just look at it, rollup the lip once and GIVER and yeah it works out fine
Feb 2 2006 10:07AM
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Melvs
Posts: 15174 - Karma: 480
what we need is someone who's into physics to write a simple program witha nive GUI that would left you set all these factors (IE angle of takeoff, type of snow [which would have a rough estimate for coefficiant of friction per type of snow] wind speed and direction) and it could give you an estimate of what speed you need pretty easily. Then you could also see a few rough estimates of how far on a certain angled slope you would need to travel by straightlining to give you the needed speed.

hmmm... I don't it'd be that hard... anyone wanna do it?
Feb 2 2006 10:13AM
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Itsbackfliptime
Posts: 18901 - Karma: 75
^hmm I may take some time and do it.
Feb 2 2006 10:19AM
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RRhighrider
Posts: 2141 - Karma: 1,141
you could have a good guess but there are more forces in action and varibles then anyone here could really understand. if you want a complete understanding of the physics of skiing i suggest you read "the physics of skiing at the triple point" you need some physics and engineering backround to understand evreything but it explains the factors involied in skiing pretty well.
Feb 2 2006 11:18AM
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ifsa_alum
Posts: 355 - Karma: 10
Be sure to include a legal disclaimer absolving the software program and its author of any accidents incurred, including death and dismemberment, as a result of possible erroneous data, in either input or output.

For entertainment purposes only.

In other words: fuck yourself up, and it's your own fault, jackass.
Feb 2 2006 11:25AM
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Itsbackfliptime
Posts: 18901 - Karma: 75
^true
Feb 2 2006 11:32AM
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00000000
Posts: 11075 - Karma: 82,508
I did my physics paper on it, calculated the minimum and maximum speeds needed to clear 3 different size jumps, and I used 5 different types of jumps. You pretty much have to use 5-6 different formulas since their are many factors (ie angle of lip). I also figured out which jumps would be the worst to undershoot/overshoot
Feb 2 2006 11:35AM
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awsomecoolguy
Posts: 3536 - Karma: 13
these are the smart kids of ns
Feb 2 2006 11:43AM
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Melvs
Posts: 15174 - Karma: 480
Randall, are you at U of M for physics?
Feb 2 2006 12:59PM
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sampsihoyos
Posts: 1939 - Karma: 910
distance= rate x time + acceleration x time squared
thats it
Feb 2 2006 1:04PM
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leone
Posts: 2663 - Karma: 1,121
it's not that hard to figure out, you just need to split into an x and y axis, know the distance, height, and angle and maybe one more thing but other than that it's easy (AP Physics this year)
Feb 2 2006 2:15PM
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MdanteL
Posts: 1142 - Karma: 16
v= d/t... for instance Chad's.. to the find the velocity you need to clear chads u do 130/the amount of time you are in the air
Feb 2 2006 2:17PM
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Aseets
Posts: 2171 - Karma: 17
It wouldn't be that hard for park jumps, all you neeed to knwo is the angle and speed and length of the hit, and with all the rough uncertain spots you can just make a longer landing and longer inrun to accomodate for slow/fast snow
Feb 2 2006 2:20PM
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BillyGoteMan
Posts: 1983 - Karma: 12
well its like a two dimensional anylisis, not a hard problem to do, could even factor in how long the inrun should be to get to that speed.
Didn't tanner have a speed gun on hand when he hit chads?
Feb 2 2006 4:08PM
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heymanitsdan
Posts: 175 - Karma: 10
we need lachance
Feb 2 2006 4:31PM
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nickmcnutt
Posts: 4396 - Karma: 2,966
but its not like they could say "stop! you are going too slow!" at 55 mph at the end of a huge chasm
Feb 2 2006 4:35PM
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Jessbuff
Posts: 2685 - Karma: 17
Man, I've got a biomechanics midterm next week and I don't know shit.

However, my prof for the course has done research with skiiers. I think they were arialists, but whatever. He used all sorts of crazy math to figure out how they needed to position and move thier bodies in order to maximize the speed they spun etc. Pretty crazy stuff.

I kindof doubt they do too much with freestyl skiing, given that guys don't train for it, they just go out and rip on a regular basis.
Feb 2 2006 4:53PM
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Djphantom
Posts: 124 - Karma: 10
Guys you forgot one other factor that is important. Your skis! The lenght, the last type of wax used, if you have any big scratches, etc.
Feb 2 2006 5:01PM
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Powdahound
Posts: 522 - Karma: 9
this doesn't apply in the chads gap scenario but if your going to slow, they tell you.. wave their arms or whatever you could easily change direction and not hit it, you dont have to come to a complete stop always
Feb 2 2006 5:24PM
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Itsbackfliptime
Posts: 18901 - Karma: 75
i got a c- in physics. I'm there for computer science though.
Feb 2 2006 6:21PM
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Melvs
Posts: 15174 - Karma: 480
even better. Write it!!!
Feb 2 2006 6:45PM
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NWFlow
Posts: 1557 - Karma: 61
That's actually a pretty sweet idea. I was going to complain about there being too many variables but a well-designed computer program would be able to factor in almost all of the variables (NUMB3RS anyone? haha). You could even hook it up to a TI-89 plus so you could do the calculations right there in the field. With a radar gun, you'd be set.
Feb 2 2006 7:55PM
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jibs
Posts: 2529 - Karma: 48
Check the revived 'gap calculator' thread
Feb 2 2006 9:47PM
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squeakywaffle
Posts: 1800 - Karma: 13
calculating everything assuming a vacuum is easy, but air resistance increases roughly as the square of the velocity... and try calculating the drag profile of a flying skier.

small gaps sure, but big gaps at 60+ mph are going to be a whole different ball game.
Feb 2 2006 11:13PM
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JIB_NISSE
Posts: 833 - Karma: 28
that wouldnt really work precisely, what you would use is: a combination of projectile and circular motion and GPE=KE and a bit of friction, (however its hard to find the coefficient of friction of snow since the temp. changes)and the riders weight and airresistance(if you want to be accurate.)
Feb 3 2006 7:38AM
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