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FiFi LaFeles

FiFi LaFeles

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Dracule said :
Aeroxmaster said :
Many Much said :
Rigor mortis.

When a person dies, there is a process that starts in the corpse.
Protein in the muscles will start hardening.


The protein doesn't harden but I know what you mean.

Muscle contraction requires something called ATP (Adenine Triphosphase); which essentially is the currency of 'energy' the human body uses.

After a person dies, muscles can still temporarily contract and relax because they still have a concentration of ATP left. Once the ATP is depleted, the muscles enter a constant state of contraction because of the Calcium ions facilitating the protein bridges. With no ATP, myosin - one of the proteins in the bridge - cannot be moved and so the bridges cannot break.

This is Rigor mortis.



Interesting, never knew that. But Rigor isn't permanent so what happens to 'make it go away'?
Le Chat Guerrier

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07-Jun-2015 10:16:26

Dracule
Mar Member 2020

Dracule

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RubiksCube77 said :
I'll make my educated guess here.

Hey!

You raised some very good points in your posts. Perhaps one little error I found is when you defined torque here (unless I've misread). Torque is defined as a cross product between a force and a length, where length represents the distance away from the axis the object is being rotated on. So yes, you would be correct in saying the position of the phone will indeed affect the torque.

I do see where you went when you mentioned Moment of Inertia isn't the only thing in play in the phones unsteady rotation. But with this I must disagree because mathematically speaking, the proof behind the unsteady rotation is actually irrespective of any torques.

If we assume i1, i2 and i3 as principal moments of inertia on the principal axis (horizontal, intermediate and vertical respectively), they would be ordered like this: i1<i2<i3, i3 (vertical) having the largest inertia because it requires the most torque - you can try this yourself.

The Intermediate Axis Theorem states that on the axis with i1 and i3 applied, the objects rotation will be stable. An object rotating on the intermediate axis will be unstable. Mathematically, the proof is kind of complex and quite annoying to type on an iPad but it's similar to that of a rigid pendulum.

If you applied a 3D system of Euler's rotation equations equated to zero (so no torque), substitute in the principal inertias mentioned above and a couple of parameters out with new perturbation parameters, then through some algebraic manipulation and differentiation you'd have three equation systems for each axis reduced to one. The most relevant terms are the constants in these three equations as shown below.

Horizontal axis: ((i3 - i1)(i1 - i2))/(i2 x i3)
Intermediate axis: ((i1- i2)(i2- i3))/(i3 x i1)
Vertical axis: ((i2 - i3)(i3- i1)/(i1 x i2)

Subject to i1< i2< i3





Continued...
¸‹^¹´', ¸¸·¸·¸¸ ,'`¹^›¸
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Dracule
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'·ˆ·'
.………
I don't like steak
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'·ˆ·'

07-Jun-2015 21:41:55 - Last edited on 07-Jun-2015 22:20:20 by Dracule

Dracule
Mar Member 2020

Dracule

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Now, if the value of the constant is negative, then it means the solutions will be oscillatory - they'll just keep going back and forth. Physically this would mean the rotation would hold its steadiness if there was slight perturbations in it. Therefore, the rotation is stable .

However, if the value of the constant is positive, then the solutions would only exponentially increase. Now this physically means any perturbation away from the rotation axis the object is spinning on would be magnified, until it is unable to rotate steadily without going on a different axis. Therefore in this case, the rotation would be unstable .

Using the constraint given above and some arithmetic knowledge you'd be able to see that the horizontal and vertical axis equations provide negative values, while the intermediate gives a positive value. So this means a rotation on this axis will almost always be unstable (I say almost because it's theoretically possible to get a perfect phone flip on the intermediate axis).

Taking all the mathematics out of this and giving a broader perspective of everything I just explained, you can try this out with an object like a walking cane. Dangle the cane by putting the handle on a finger and give it a little tap - you can see the cane swing back to its original position, like a pendulum. Now turn the cane and try to balance it on top of your finger, notice how it's harder to do? Any unsteadiness in the balance can magnify until the cane falls off!

________________________________

Therefore you cannot flip your phone end over end without it rotating in a different direction!

(Phew...)
¸‹^¹´', ¸¸·¸·¸¸ ,'`¹^›¸
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Dracule
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¸‹^¹´', ¸¸·¸·¸¸ ,'`¹^›¸
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………………..
' ´`· ˆ , -¸ . ¸- , ˆ ·´` '
'·ˆ·'
.………
I don't like steak
……….
'·ˆ·'

07-Jun-2015 21:42:22 - Last edited on 07-Jun-2015 22:21:11 by Dracule

Dracule
Mar Member 2020

Dracule

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FiFi LaFeles said :
Interesting, never knew that. But Rigor isn't permanent so what happens to 'make it go away'?

It disappears during the decomposition process. Bacterial enzymes break down the myosin, so the bridges break and muscles relax.
¸‹^¹´', ¸¸·¸·¸¸ ,'`¹^›¸
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Dracule
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¸‹^¹´', ¸¸·¸·¸¸ ,'`¹^›¸
' ´`· ˆ , -¸ . ¸- , ˆ ·´` '
………………..
' ´`· ˆ , -¸ . ¸- , ˆ ·´` '
'·ˆ·'
.………
I don't like steak
……….
'·ˆ·'

07-Jun-2015 22:32:08 - Last edited on 07-Jun-2015 22:32:45 by Dracule

RubiksCube77
Nov Member 2021

RubiksCube77

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Thanks for the correction Dracule. Looks like I have some reviewing to do.

I did a bit of researching on the stages of death since there was a question on rigor mortis. What I found was that there are seven stages of death.

Pallor mortis: Skin becomes pale because blood sinks down to the power parts due to gravity and this leads to livor mortis.

Algor mortis: The reduction of body temperature after death.

Rigor mortis: already covered

Livor mortis: blood pools in the lower parts of the body (let's say the body is flat on its back; the blood pools there) and causes a purplish red discoloration.

Putrefaction: the decomposition of proteins that would eventually lead to the breakdown of cohesion between tissues and liquefaction of most organs.

Decomposition: Organic substances are broken down into a much simpler form of matter.

Skeletonization: The final stage of decomposition where the soft tissues have decayed or dried to the point where the bones are exposed.

I was going to say that rigor mortis disappears when putrefaction begins, but you're probably right on this one though since you seems to know much more about the natural sciences than me.

Interesting thing I did come across when I was reading about the stages of death. The skeleton is not permanent. The acids in a soil can actually reduce the remains even further. And this was one reason why there was a lack of human remains found in the wreckage of the Titanic.
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08-Jun-2015 00:49:37

Many Much

Many Much

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@Jokku.

Yea, Pokemon will have different stats on lv 100, depends how you trained it and on what kind of hidden stats it got.

An example: just catch two same species Pokemon on same level and compare them. The stats will be different by a hidden stat value.

And there is many websites that you can enter your Pokemon's stats there and use their calculators to find out your stats and hidden stats (IV)
How many much more do you want?
:P :P :P

08-Jun-2015 15:37:36 - Last edited on 08-Jun-2015 16:01:36 by Many Much

Dracule
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Dracule

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RubiksCube77 said :
Putrefaction: the decomposition of proteins that would eventually lead to the breakdown of cohesion between tissues and liquefaction of most organs.

Decomposition: Organic substances are broken down into a much simpler form of matter.

I was going to say that rigor mortis disappears when putrefaction begins,

The whole process of the body breaking down after death is what is known as decomposition, by definition I believe and yes, there are stages of such a process as you've already mentioned, like Rigor, Algor, etc.

I see a little bit of a tautology in what you wrote because to my knowledge, proteins fall under the chemical definition of an organic substance and seeing as the majority of the human body is composed of organic material. Your definition of decomposition in my opinion, would better fit the entire process; with Putrefaction making up a part of it.

4A6F6B6B75 said :
@Dracule

I have never heard of that Intermediate Axis Theorem, but I found a nice video about it on Youtube. Sounds interesting, thanks.

I'm glad you, NoName and others here find interest in my posts! Most other people I talk to don't seem to care for any geeky things I may say, haha :)
¸‹^¹´', ¸¸·¸·¸¸ ,'`¹^›¸
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Dracule
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¸‹^¹´', ¸¸·¸·¸¸ ,'`¹^›¸
' ´`· ˆ , -¸ . ¸- , ˆ ·´` '
………………..
' ´`· ˆ , -¸ . ¸- , ˆ ·´` '
'·ˆ·'
.………
I don't like steak
……….
'·ˆ·'

08-Jun-2015 16:51:19

VVinh

VVinh

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Joseph Jastrow's duck or rabbit illusion.
Anyone heard about it?
Jastrow illusion is when two identical (same and same sized) items are beside each other and one looks bigger than the other one. Our eyes give the brain false signals so with thinks that one is bigger since they both are same.

Another example of illusion:
Which one is further?

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I'm gaÿ.

08-Jun-2015 21:54:14

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