BigZeeff

Hey all,

I was having this discussion with my roommate on snowboard physics and couldn't agree on an answer, so here I am. Here's the question.

Which snowboarder will get to the bottom of a hill faster, considering they are same weight, etc. The snowboarder who pumps with his legs to do jumps and rely on less friction in his air jumps, or the snowboarder who continues forward and doesn't lose momentum by jumping and hitting the ground over and over again and keep a slick friction. Keep in mind that the jumps are leg pump jumps, not ramp jumps. Thanks!

PaoloSmythe

tis an interesting question.

the ansa, is that air time = slow time.

now the limitation on my explanation as to why this is, is that air resistence slows you down as though you're a sail... but why such fails to apply on the ground i do not know.

also, altho your board essentially creates warm friction to melt the snow and thus allow you to slide, this is still friction, so shouldn't this add a tiny bit to the slowness?

i am bamboozled!

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kri$han

well, the way I see it is that in both cases, air resistance will be constant, so you can't really consider that (whether you're flying through the air, or on the ground, air is still there).

I don't think there's a way to prove this, but my hypothesis is that the guy that stays tucked and rides all the way down will get to the bottom first. Simply because, if you were to straight-line a hill, you're pretty much accelerating down the hill constantly.

Now if one was 'jumping' (or ollie-ing, right? ) you'd be interrupting this constant down-hill acceleration by applying a force downwards and thrusting yourself upwards. Granted, when you are 'falling' from your jump, you'd be accelerating faster than if you were on the snow, but the constant thrusting upwards would keep limiting your speed, imo.

Honestly, the ONLY way to truely know is to test it, since there really is no formula or way you could prove this with theory.

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Kris
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nzboardlife

horizontally(as you are a projectile) you will always both be traveling at the same speed, except the one hitting jumps gets slowed down by the vertical incline of the jump... i think.



^^^^ there acceleration is exactly the same at all times, 9.81 ms^-2 downwards

kri$han

Of course their free fall acceleration is 9.81m/s^2, indeed, but you'd have to multiply that times a comonent of each riders weight (since they're not going down a 90degree vertical), subtract friction and air resisitance, and (like I said) one would be constantly accelerating, while the other intermittently accelerating upwards.

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Kris
Toronto Prelude Club

boardy___

edit: yeah what he said ^^^


im guessing the person who doesn't jump wins

the air friction doesnt matter but as you land from a jump some force vertical force is lost as you absorb the landing. also at the peak of the airborn parabola vertical acceleration is 0 where as if you dont jump you are constantly accelerating at a tangent to the force of gravity...? can someone who actually knows what they're talking about correct me

PaoloSmythe

so i guess the momentum of going down hill, is reduced due to the 'upward' trajectory' caused by taking flight....

with points being A to B (top to bottom) any deviation from this, is to lengthen the 'straight line' which is the shortest and thus fastest way from point to point. so flight = greater distance.

also the arch of the airbourne flight path sees the upward momentum (lift off) being countered by the ever present force of gravity (to bring you back to earth).... a gravitational force which could be better used to get you to the 'finish line'.

ie gravity has to work to bring you back to earth before it can continue to drag you to the bottom of the slope.

makes sense to me!

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mpdsnowman

We used to talk about stuff like this when I was a ski racer..

Here is the deal. The person who continues forward will win because that individual will take on less air. Air is your worst enemy when it comes to speed/distance analysys... The one who is bouncing around is picking up air and is actually slowing down their speed..

Thats why it is critical in say a bordercross event. Each one will hit air intently. The one who keeps the lowest tuck and remains closest to the actual ground will stay ahead and win.

Keep in mind with the laws of physics...both of equal weight(exact weight) and equal pitch and distance they will both reach their plateau on speed(again if everything is perfectly equal)..Air is the only difference that will effect the speed and the continued velocity of the race.

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M P D S N O W M A N

pawlo

well the fact that everytime you land a jump you weight more ( mass) and dig into the snow a bit for the added mass will slow you down, because of the more friction you generate each landing.

If the jumper rider could "fly" down never touching the snow he/she will be faster.

Mooz

Epic physics fail. Your mass is constant. Your momentum changes when you jump and land as well as your directional force. MPD was right about air time though. You have two forces attempting to slow you down. Friction from board on snow and friction from air resistance. Also remember the shortest distance between two points is a straight line. Jumping creates an arc. You'll also dramatically increase wind resistance by going airborne. Sure you lose the friction from the snow but you're also removing your downward momentum in favor of an airborne momentum and arc. You're also losing that which you need most. Momentum from the angle of the mountain.

The fastest rider will be the one that stays on the ground tucked in tight. The "flying" rider (jesus that made my head hurt) is still slower because they lack anything to propell them downward aside from gravity and they still have to deal with the incredible amount of wind resistance. Gravity is up and down you still need momentum to traverse the hill unless it's a cliff. If it's a cliff all bets are out since they're both going to be dead on impact anyway.

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