inclination的数学模型

jluo

The term body weight is the physical absolute downward force caused by gravity due to weight; centripetal force is however acting on the the relative datum of ski slope. From his formula, I believe what he was referring to are actually the (two main static) forces. what he missed is that MOMENT is calculated as F x l, l being the moment arm. The body position plays a very critical role in determining the moment arm. If we hold our body to become a rigid body object, the moment arm for both forces are both roughly the length between edge of ski to cg, however with the dynamic motion and change of terrain condition, I believe the moment arm for weight actually shortens while that for centripetal elongates. meanwhile, the composition factor for both forces would change also.

of course, I might be wrong

jluo

我就是个吹牛的，看不懂不管，说错了不负责。

Bingster

学好数学才是最fundamental的东西啊，没有数学的精确计算和推论，物理靠什么来说服别人？滑雪就更是这样了~

这个 Topic 太学究气了。用数学物理来算滑雪？我不信会有帮助。
到是从另一个角度看文题。

bullpower

Bingster 发表于 2011-4-22 09:53
这个 Topic 太学究气了。用数学物理来算滑雪？我不信会有帮助。
到是从另一个角度看文题。
...

那是你水平还没到那个级别。

所有体育运动到达顶尖标准，全是在拼高科技，我就列举几个我熟悉的运动：

球类运动：
                 球路分析，习惯性的进攻路线和得分手段=== 都是从大量比赛录像里DATA MINING出来的
                球拍的性能，最佳挥拍动作，击球点。。都是算出来的。。。我知道排球比赛： 现在比赛里，
                多台摄像机在观众席上实时拍摄，助理教练用计算机随时统计对方的进攻路线，二传的组织球路。。
                主教练戴着耳机，随时听数据反馈

游泳：在静止池里游，就是为了一个动作一个动作的细扣，合理性。

这些都是数学/物理。 你去看看体育专业的论文，里面数学，物理的东东不少地。
我认识一个高中球友（ONTARIO U19铜牌哦），他高中就写过论文，论证劈吊时， 球的转速与落点的关系。。。。

滑雪需要理论和高科技的地方一定不少。

想咱这样的业余水平，当然用不到，也烧不起那粪土，主要是数学物理都忘了，基本看不明白。。。。

我想真到LEVEL 4了，自然也需要了。

jluo

noodle snow ==>

"the moment arm for both forces are both roughly the length between edge of ski to cg" this is wrong. for weight it's sin(alpha) x that length, and for centripetal force it's cos(alpha) x that len

the sin/cos are the composition of the force, which I think I conveniently left out the composition. to me the weight force component is actually mg.cos(a), and the centripetal has 3 components, the balance force, the normal support, and the angular acceleration (turning force)

jluo

I didn't mean the formula was wrong, I just think the formula is presentation of forces, and the consideration of moment arms are also important, but skiing is very dynamic and complex, so if you balance, you are doing it right :D I leave the real deal to the pros,

lupo

你们都学过matlab的？大学的时候学过一年，博士前的时候用这个做数据分析，当时的课题是温度及地理位置对购车者得影响，还有癌症病例分析成活率等，这个软件牛叉的。

jluo

let's just leave it to the pros :D ...

jluo

that is why there are we engineers :D

jluo

iEngineer ;)