Yet ANOTHER physics question

[layton]

Ok, it's really a geometry question. I've heard of this theory (and actually put it in my first book). But it doesn't make sense. How do you get 30 degrees and 3 degree each additional cm?

Bruce Tremper illustrates it in "staying alive in avalanche terrain".

 

picture reposted below

Edited February 3, 2014 by layton

[layton]

if someone can repost the image smaller, i'll delete the original hogging the screen. can't seem to figure out how to post images right

[Drederek]

an equilateral triangle with the dangling side vertical yields a 30 degree slope. the 10 cm thing would only be accurate for 1 3 degree increment if your pole was the correct length. but it may be close enough for you

[num1mc]

For the photobomb challenged

 

 

[genepires]

an equilateral triangle with the dangling side vertical yields a 30 degree slope.

 

when the slope is 30 degrees, a equilateral triangle is made and the angles inside the equilateral triangle are 60 degrees. when compared to the horizon (angle of slope in question measured from the horizon) , the pole always creates a 90 degree angle with the 30 degree for slope and the 60 degree inside triangle.

 

 

Edited February 2, 2014 by genepires

[genepires]

a triangle is formed (by the poles for all angle of slopes) in which the bisector of the top angle forms and angle equal to the slope angle. Lets call that angle Z.

 

using the sine rule, sin (Z) = (length of snow slope from two pole interactions with snow/2) / length of pole. to simplify, lets call it sin (z) = length between baskets / 2 ski pole lengths. to simplify it more, length between basket = sin(Z) * 2 ski pole lenghts

This a labeled version of the sin Z = opposite / hypotenuse.

 

from this you can put in the length of pole and then plug in z=30, z=33, z=35, ect. to find if that trend is there for your pole length and also if it follows for angles over 45 degrees. (I don't have a good calculator with me now)

 

I suspect that it will not as the trig is not a linear function. Right around 45 degrees it is somewhat linear so the idea that it will change a fixed amount over a fixed degree change is expected.

 

the short of the long is that if you are anal about numbers, the idea of a constant degree change over a fixed length change is false. but good enough for having "phun" work.

 

also, it depends on the pole length too.

 

also depends on ball sack size.

[layton]

ahhhh

[genepires]

will draw it out on paper later for ya buddy.

[tvashtarkatena]

Three simple tricks for measuring 3 critical slope angles a skier might care about. You can eyeball perpendicularity to within +/- a couple of degrees or so.

 

Slope Angle w Ski Poles by PatGallagherArt, on Flickr

Edited February 7, 2014 by tvashtarkatena