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舊 2015-04-25, 11:42 AM   #1
B2L2
滑雪瘋3級
 
註冊日期: 2011-03-04
文章: 346
預設 COM

你們可否把自己的COM放到身體外部呢?我得,你得唔得丫?

可能有人腰又彎不了,手腳又只可兩邊飛,所以係做不來的。
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舊 2015-04-25, 10:02 PM   #2
taichiskiing
滑雪瘋7級
 
註冊日期: 2009-02-07
文章: 3,756
預設 回覆: COM

引用:
作者: B2L2 查看文章
你們可否把自己的COM放到身體外部呢?我得,你得唔得丫?

可能有人腰又彎不了,手腳又只可兩邊飛,所以係做不來的。
No, you cannot move your COM to outside your body, (outside of your body there has no [body] “Mass,”) if you do, I like to see it.

:)
IS
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舊 2015-04-26, 12:08 PM   #3
B2L2
滑雪瘋3級
 
註冊日期: 2011-03-04
文章: 346
預設 回覆: COM

You obviously didn't know what COM means.
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舊 2015-04-26, 10:43 PM   #4
taichiskiing
滑雪瘋7級
 
註冊日期: 2009-02-07
文章: 3,756
預設 回覆: COM

引用:
作者: B2L2 查看文章
You obviously didn't know what COM means.
Well, let's hear it, what does your “COM” mean?

:)
IS
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舊 2015-04-29, 11:30 PM   #5
pku
滑雪瘋7級
 
註冊日期: 2010-05-30
文章: 3,787
預設 回覆: COM

引用:
作者: taichiskiing 查看文章
Well, let's hear it, what does your “COM” mean?

:)
IS
請問你為何休息差不多兩個月沒有發言
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舊 2015-04-30, 02:58 AM   #6
taichiskiing
滑雪瘋7級
 
註冊日期: 2009-02-07
文章: 3,756
預設 回覆: COM

引用:
作者: pku 查看文章
請問你為何休息差不多兩個月沒有發言
1. Skiing, of course, I have so much fun “improving” myself, no time to waste on you gappers. Due to the California drought, Heavenly had an exceptional bad year. Some tree runs were open for a very short period of the time and barely skiable, not really, and I didn't want to ruinning my skis, so we mostly stayed on the groomed runs, and it was “warm” all season, I called it “a season without winter,” so it is basically “spring skiing” all season. Due to the snow conditions, spring skiing, cannot go fast, as the snow would grab your skis and kill the the speed, and cannot slow down, as the gravity continues to pull you downward, it is very tedius skiing if one doesn't know how to handle the snow. But she nailed it, so we were really having fun.

Whitecrane skiing: Spring skiing, 2015 - YouTube



at the end of the clip check out the bare terrain across the trail, and this run is in the “best” snow condition of the season.

2. I was checking how you gappers converse without me present, same old same old, without my arguments you guys cannot even make meaningful conversations, so boring even beg missed me. Yup, I do need to take a break from you gappers, so it went.

:)
IS
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舊 2015-04-30, 06:14 AM   #7
beg
滑雪瘋6級
 
註冊日期: 2010-07-10
文章: 2,094
預設 回覆: COM

引用:
作者: taichiskiing 查看文章
1. Skiing, of course, I have so much fun “improving” myself, no time to waste on you gappers. Due to the California drought, Heavenly had an exceptional bad year. Some tree runs were open for a very short period of the time and barely skiable, not really, and I didn't want to ruinning my skis, so we mostly stayed on the groomed runs, and it was “warm” all season, I called it “a season without winter,” so it is basically “spring skiing” all season. Due to the snow conditions, spring skiing, cannot go fast, as the snow would grab your skis and kill the the speed, and cannot slow down, as the gravity continues to pull you downward, it is very tedius skiing if one doesn't know how to handle the snow. But she nailed it, so we were really having fun.

Whitecrane skiing: Spring skiing, 2015 - YouTube


at the end of the clip check out the bare terrain across the trail, and this run is in the “best” snow condition of the season.

2. I was checking how you gappers converse without me present, same old same old, without my arguments you guys cannot even make meaningful conversations, so boring even beg missed me. Yup, I do need to take a break from you gappers, so it went.

:)
IS
Yup, we all miss you here, I miss to kick your ass so much. ski with your comfort zone . You'll enjoy it. Don't go any further like mogul or use pole because that make you look like beginner.

此篇文章於 2015-05-01 02:54 AM 被 beg 編輯。
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舊 2015-05-01, 10:08 AM   #8
B2L2
滑雪瘋3級
 
註冊日期: 2011-03-04
文章: 346
預設 回覆: COM

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舊 2015-05-01, 10:30 PM   #9
taichiskiing
滑雪瘋7級
 
註冊日期: 2009-02-07
文章: 3,756
預設 回覆: COM

引用:
作者: B2L2 查看文章
You mean you live in a “zombie world”? no, we human have muscles and skins, COM cannot move out of our “body.” For a “香港大學的高材生”的學歷, your concepts on math and physics, 東抄抄西抄抄, are pathetic.

:)
IS

此篇文章於 2015-05-01 11:13 PM 被 taichiskiing 編輯。
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舊 2015-05-02, 03:03 AM   #10
B2L2
滑雪瘋3級
 
註冊日期: 2011-03-04
文章: 346
預設 回覆: COM





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舊 2015-05-02, 03:26 AM   #11
taichiskiing
滑雪瘋7級
 
註冊日期: 2009-02-07
文章: 3,756
預設 回覆: COM

引用:
作者: B2L2 查看文章




No, we human are not dummy neither, on the middle two drawings, they show COM are on the outside of the body, but a real person would use muscles and skins' tension to keep the COM inside the body. If your COM “falls” (physics term, which means “follow the gravity,”) outside of the body, the body “falls” (normal term) to the ground.

:)
IS
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舊 2015-05-02, 03:45 AM   #12
B2L2
滑雪瘋3級
 
註冊日期: 2011-03-04
文章: 346
預設 回覆: COM

In physics, the center of mass is a point in space where the weighted relative position of the distributed mass sums to zero.

As simple as that. It has nothing to do with gravity, external force. Just mass in space. Don't mistake it with the center of gravity. These two points could be consider the same in a uniform gravity field.

The human body's center of mass is always changing because it is not a fixed shape. In certain pose, the center of mass of a human body could be "outside" of his body.

High jumper is a typical example being used a lot. They bend their body and legs in way so that they body clear the bar, even their COM pass under the bar.
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舊 2015-05-02, 04:56 AM   #13
taichiskiing
滑雪瘋7級
 
註冊日期: 2009-02-07
文章: 3,756
預設 回覆: COM

引用:
作者: B2L2 查看文章
In physics, the center of mass is a point in space where the weighted relative position of the distributed mass sums to zero.
What does that mean? What is the “weighted”relative position, and how do you get the “weight” into the “mass”?

引用:
As simple as that. It has nothing to do with gravity, external force. Just mass in space. Don't mistake it with the center of gravity. These two points could be consider the same in a uniform gravity field.
No, without gravity, you don't have “weight,” so the “the ‘weighted’ relative position of the distributed mass sums to zero,” so, in 0G, there's no COM; under gravity, the gravity is considered acting on the Center of Gravity (CG), where “the weighted relative position of the distributed mass sums to zero,” that is the COM, COM in physics is mostly referring to CG, and you cannot have your CG outside of your body and still maintain balance.

引用:
The human body's center of mass is always changing because it is not a fixed shape. In certain pose, the center of mass of a human body could be "outside" of his body.

High jumper is a typical example being used a lot. They bend their body and legs in way so that they body clear the bar, even their COM pass under the bar.
High jump IS a good example, but you are for the wrong reason. The reason the high jumper can make the jump is because he puts the COM outside of his or body, where the COM leads the body “falls”with gravity like a canon ball flies through the air, high jump is to utilize the “imbalance” property of COM.

:)
IS
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舊 2015-05-02, 05:27 AM   #14
B2L2
滑雪瘋3級
 
註冊日期: 2011-03-04
文章: 346
預設 回覆: COM

Nice, you have a math degree and don't know what's "weighted" mean. And your English is equally bad.

"Weighted" is not a noun. "Weight" is a noun.

Weighted average, weighted sum is an arithmetic term. Go check your 101 text book and correct you whole argument.

Again, COM has nothing to do with gravity or force. It is mass only. Even in 0-G environment, an object still have COM.

(No one is talking about motion or movement here. Even, that you're still wrong.)
Maintain balance? On what? On the floor? And yes, human could have a COM outside of his body and still maintain balance. Above pictures illustrated how. Do you know why?

And finally you said and agree that a high jumper could put the COM outside of his body. Thanks for agreeing.

此篇文章於 2015-05-02 05:31 AM 被 B2L2 編輯。
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舊 2015-05-02, 07:47 AM   #15
taichiskiing
滑雪瘋7級
 
註冊日期: 2009-02-07
文章: 3,756
預設 回覆: COM

引用:
作者: B2L2 查看文章
Nice, you have a math degree and don't know what's "weighted" mean. And your English is equally bad.

"Weighted" is not a noun. "Weight" is a noun.
Not sure how good your English is neither; “weighted” is a p.p., serves as adj., and adj. can serves as noun sometimes. Yup, “your English is equally bad.”

引用:
Weighted average, weighted sum is an arithmetic term. Go check your 101 text book and correct you whole argument.
Yeah, in other words, you don't know what they mean.

引用:
Again, COM has nothing to do with gravity or force. It is mass only. Even in 0-G environment, an object still have COM.
No, you “無恥鐵齒” won't make it right. All “weighted” mass in 0G is 0, so, the “sum” of “weighted mass” is 0, so the whole object is the “Center of Mass,” or the other way of saying, “No COM.” You are confused “weighted mass” with “mass.”

引用:
(No one is talking about motion or movement here. Even, that you're still wrong.)
Maintain balance? On what? On the floor? And yes, human could have a COM outside of his body and still maintain balance. Above pictures illustrated how. Do you know why?
“You are a joke,”without “motion or movement,” there won't be any “force” or force equals to 0/zero, and only then, there's “balance.” When there's no “motion or movement,” the balance is called “static balance.” If an object moves but can return to the “static balance,”we called that “dynamic balance.” When an object moves, but cannot return to its “static balance,” then there would be a “fall with the gravity,” normal term, just “fall.” Kick around a chair, you'll find out. Now, how do you think those objects maintain “balance”in those pictures?

引用:
And finally you said and agree that a high jumper could put the COM outside of his body. Thanks for agreeing.
No, it is the “force” projects the COM to outside of the body, but the COM still remains inside the body, thus can move the “whole” body forward. You remain wrong.

:)
IS
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舊 2015-05-02, 09:56 AM   #16
B2L2
滑雪瘋3級
 
註冊日期: 2011-03-04
文章: 346
預設 回覆: COM

Who created the team "weighted mass"? I don't. I don't know how u got confused. If u want to use that team, please defined what it is.

U seriously don't know what's a "weighted function"? A "weighted function" gives more influence on some elements when performing a sum or average calculation.

In COM, the influence is the mass distribution. So far, nothing to do with how heavy the object is which people call that "weight". And again, nothing related to force, gravity, motion, movement.

That's my definition of COM and you could easily search on the internet. If u don't agree, go let me what's your definition, better come with supports.
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舊 2015-05-02, 10:02 AM   #17
B2L2
滑雪瘋3級
 
註冊日期: 2011-03-04
文章: 346
預設 回覆: COM

引用:
作者: taichiskiing 查看文章
The reason the high jumper can make the jump is because he puts the COM outside of his or body, where the COM leads the body “falls”with gravity like a canon ball flies through the air, high jump is to utilize the “imbalance” property of COM.
It is your own word. You said high jumper could put his COM outside his body. Which part is confusing? Now he cannot do it?
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舊 2015-05-02, 10:39 PM   #18
taichiskiing
滑雪瘋7級
 
註冊日期: 2009-02-07
文章: 3,756
預設 回覆: COM

引用:
作者: B2L2 查看文章
Who created the team "weighted mass"? I don't. I don't know how u got confused. If u want to use that team, please defined what it is.
You did, when you “東抄抄西抄抄” from Wikimedia.com without knowing what you are “東抄抄西抄抄” about, and I did ask you to clarify, but you shamelessly ducked the question.

引用:
作者: B2L2 查看文章
In physics, the center of mass is a point in space where the weighted relative position of the distributed mass sums to zero.
What does that mean? What is the “weighted”relative position, and how do you get the “weight” into the “mass”?”

引用:
U seriously don't know what's a "weighted function"? A "weighted function" gives more influence on some elements when performing a sum or average calculation.
No, can't say I do. What I know is that “weighted function” is a statistics term, and I didn't have any statistics classes in college. Nevertheless, according to your “東抄抄西抄抄”的 definition, “A "weighted function" gives more influence on some elements when performing a sum or average calculation,”(e.g. in survey of people's opinions, etc.,) which has nothing to with the “weight” of the people, so, you have totally lost what “COM” is all about.

引用:
In COM, the influence is the mass distribution. So far, nothing to do with how heavy the object is which people call that "weight". And again, nothing related to force, gravity, motion, movement.
Yup, “you have totally lost what “COM” is all about.”

引用:
That's my definition of COM and you could easily search on the internet. If u don't agree, go let me what's your definition, better come with supports.
Of course, your “definition of COM” is “copy&pasted” from internet, and more precisely, Wikimedia, but no, it is too technical, you don't know what you are copying. I did give my definition, COM=CG under “gravity,” and “no COM” in 0G, again, it is too technical for you to understand, which also confirm what I said “you are not a math/physics/sci person.” What is your “bachelor of science” degree major in, again?


引用:
作者: B2L2 查看文章
It is your own word. You said high jumper could put his COM outside his body. Which part is confusing? Now he cannot do it?
No, he can't, if he did, his body would have a “hole” in there.

:)
IS
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舊 2015-05-03, 02:02 AM   #19
B2L2
滑雪瘋3級
 
註冊日期: 2011-03-04
文章: 346
預設 回覆: COM

You created a term, and ask me to clearify? Sorry, that something I cannot answer.

The term "weighted" refer to the "weighted function" and has nothing to do with gravity, weight of people, etc that you bring in to confuse yourself. How many times I need to repeated that. It isn't just a term used by statistics (ha, u do look it up). It is a general arithmetic term. If you don't have a text book with you, go to a library.

I'm 100% sure what's I'm talking about here and that's the COM meaning used by most people in this world. If you could prove me wrong, please have some support other than saying I'm wrong. I didn't need a physics degree to argue with you, why you care about my degree? It is just a very basic common term used by average people. Are you trying to distract this discussion again? If you ask nicely, I may tell you.

In my definition, I said that COM = Center of Gravity if it is under an uniform gravity field. You said "COM=CG under “gravity,”" Okay, we are talking about the same thing (close at least).

Now, you said “no COM” in 0G". I agree that CG is not well defined in 0G. However, under my definition where no gravity/force is required, COM still exists at the same location. One more time, my definition of COM is just mass and position, nothing to do with gravity.

There are differences between these two terms. If you don't know that, say it, and I could teach u more.

Back to human sized object living in the planet "Earth", i.e. assuming gravity G is constant through out this human body object, yes, the location of COM = location of CG. Since the COM could be put outside of a body, therefore, the CG is moved outside of his body as well.

So high jumper couldn't move his COM outside his body is your final answer. Okay.

此篇文章於 2015-05-03 04:12 AM 被 B2L2 編輯。
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舊 2015-05-03, 05:02 AM   #20
taichiskiing
滑雪瘋7級
 
註冊日期: 2009-02-07
文章: 3,756
預設 回覆: COM

引用:
作者: B2L2 查看文章
You created a term, and ask me to clearify? Sorry, that something I cannot answer.
The meaning of the term I used is based on your copy&pasted quote,

引用:
作者: B2L2 查看文章
In physics, the center of mass is a point in space where the weighted relative position of the distributed mass sums to zero.
What does that mean? What is the “weighted”relative position, and how do you get the “weight” into the “mass”?”

Both of my questions remain “valid,” you can still answer them; your wiggling to avoid answer proves that you don't know the answer—you don't know what you are talking about.

引用:
The term "weighted" refer to the "weighted function" and has nothing to do with gravity, weight of people, etc that you bring in to confuse yourself. How many times I need to repeated that. It isn't just a term used by statistics (ha, u do look it up). It is a general arithmetic term. If you don't have a text book with you, go to a library.
Yup, “weighted function” is a statistic term, but we were/are still talking about “physics,” and “COM” in particular, so it is you who confused the term. “Weighted” is not an arithmetic term, but a term in common language, check a “large” dictionary, and statistics, though has some mathematical functions, is not considered as a “math” by “pure” mathematician. “Arithmetic” is only dealing with the techniques of the calculation, has no “weighted function,” so, it is from “COM” to “weighted relative” to statistic to arithmetic, not that show you don't know the terms you used, but also show your “fields” of knowledge are “disjointed.” Whenever you tell people go somewhere to find an answer is the cue that you don’t have the answer(s). you are pathetic.

引用:
I'm 100% sure what's I'm talking about here and that's the COM meaning used by most people in this world. If you could prove me wrong, please have some support other than saying I'm wrong.
I did, but I think you even “duck” the reading, dare not to seek understanding. You gappers are all the same, you don't read my posts, and don't watch my video clips, and don't answer my questions, nevertheless, continue “無恥鐵齒”denial here, it is truly “shameless.” And “most people in this world,” just like you, cannot talk about the physical world in physics terms.

引用:
I didn't need a physics degree to argue with you since u don't have a phy degree anyway. Why you care about my degree? Trying yo hide away again? If you ask nicely, I may tell you.
“Trying yo hide away again?”? “You are a joke.” And no, as I have already proved that you are math/physics/sci illiterate, though curious, but I have no need to know what's your major now. And no, you [rude presentation] denial doesn't qualify for me to “ask nicely.”It is your "honor" at the stake.

引用:
I said it already that COM = Center of Gravity if it is under an uniform gravity field. Your definition of COM = CG is incomplete.
No, you said COM has nothing to do with gravity, even use the word "again," you liar.

“Again, COM has nothing to do with gravity or force. It is mass only. Even in 0-G environment, an object still have COM.”

http://www.goski.com.tw/forum/showpo...4&postcount=14

引用:
What's the COM of the solar system? It can't equal to its CG. There are differences between these two terms. If you don't know that, say it, and I could tell u more.
As always, I do know the answer, so I can tell you know, you don't know the answer, and if you do, your answer will be “proved” “wrong,” again.

引用:
So high jumper couldn't move his COM outside his body is your final answer. Okay.
Are you going to admit that you were “wrong”?

:)
IS
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