There is no god but physics, you - engineers, you! 
Death In Space
- Thread starter Jeff M. Hopper
- Start date
You almost owed me a new keyboard for that. :rofl:
Fritz_Brown
Super Moderator
:rofl:
This one I will actually push back on - it is the acceleration imparted by the motion of your hand that gives a sling bullet it's kinetic energy. It is actually the restrictive centripetal force holding it in the arc - rather than flying away immediately - as it accelerates, that allows it to increase in velocity.
There actually is a good reason that a decent physics teacher (or engineer) would deny the existence of a "centrifugal force": it isn't a force. There is a centrifugal effect, as Newton's law attempts to make the object travel in a straight line. [SNIP] *sigh* Never mind........ :nonono:
Vladika
SOC-14 1K
Fritz is "technically correct" which means he is absolutely correct.
Centrifugal is not a true force but an apparent force.
Real life problems involving angular accelerations are though analyzed as if it were an actual force.
This is were I noted in a previous post that engineers "tweak" the ideal universe, and its laws, to make things work.
An engineer, through years of training, and more years of practice, learn just where and how far you can deviate from the ideal to make something work safely.
Apparent force, in the real world, becomes a "force in fact" that must be delt with. I the case under discussion it overcomes the inertia of a mass undergoing vector change (acceleration, due to that vector change).
In the same vein, there is NO "force of gravity" though most people will believe to their dying day that gravity is a force. Force=Mass x acceleration (F=ma). Gravity is an attraction of two, or more, masses over some distance. In that case the acceleration, "a", is replaced in the formula by "g". The end result is the same.
Sailors also sail by the "apparent wind", not the true wind. Apparent wind is caused by the velocity of the boat, added to the true wind vector, resulting in a new, and useable vector to properly trim sails.
I would venture to say that nearly every profession, or field of endeavor, has its "tricks" and "tweaks" to both simplify and make things actually work to advantage.
So, after all that long winded discourse, Fritz is correct.
Centrifugal is not a true force but an apparent force.
Real life problems involving angular accelerations are though analyzed as if it were an actual force.
This is were I noted in a previous post that engineers "tweak" the ideal universe, and its laws, to make things work.
An engineer, through years of training, and more years of practice, learn just where and how far you can deviate from the ideal to make something work safely.
Apparent force, in the real world, becomes a "force in fact" that must be delt with. I the case under discussion it overcomes the inertia of a mass undergoing vector change (acceleration, due to that vector change).
In the same vein, there is NO "force of gravity" though most people will believe to their dying day that gravity is a force. Force=Mass x acceleration (F=ma). Gravity is an attraction of two, or more, masses over some distance. In that case the acceleration, "a", is replaced in the formula by "g". The end result is the same.
Sailors also sail by the "apparent wind", not the true wind. Apparent wind is caused by the velocity of the boat, added to the true wind vector, resulting in a new, and useable vector to properly trim sails.
I would venture to say that nearly every profession, or field of endeavor, has its "tricks" and "tweaks" to both simplify and make things actually work to advantage.
So, after all that long winded discourse, Fritz is correct.
Last edited by a moderator:
^^^
This.
All the equations in the world still have to give way to what is actually happening. The equations need to conform to the real world, not the other way around. The real world doesn't ever have to conform to the equations. The equations can be wrong - the real world can't be.
The phrase "it'll fly apart!" is real world knowledge of centrifugal force. There is actual thrust, maybe only reactionary thrust, but it is real. It is kinetic force. What we call it is just semantics.
Wait, I thought it was one of the four fundamental forces:
strong nuclear
electromagnetic
weak nuclear
gravity
I know most people make the mistake of thinking of it as the force of one big mass (planet, etc.) rather than as an attractive force between two or more masses (the average human being a rather pathetically weak source of gravitational attraction). However, I do think the physics community counts it as a force. Or did I get that wrong?
It's being argued over the last few years, as it's extremely long ranged, but also extremely weak.
Some see it as a non-force alteration of the topology of 3-D space/4-D Time-space... an alteration which causes masses to generate a force.
I can't follow the math used for those arguments, tho'.
Vladika
SOC-14 1K
Again:
Force = Mass times acceleration
Mass is that of the body's under consideration.
Acceleration is the very real tendency for those body's to move toward one another. This the a "gravity" part.
The "Force" is the product of the Mass and Acceleration (Gravity)
By the very definition, Gravity, by itself, is not and can not, be a force.
The, improper term, "Force of Gravity" should read "Force due to Gravity".
Gravity is a constituent component of force, but, by itself, is NOT a force.
Please, any engineer, or physicist on here who disagrees, pull the text you studied under and site me chapter and verse where it says otherwise. (For you others, stay away from undocumented web posting, please!)
Force = Mass times acceleration
Mass is that of the body's under consideration.
Acceleration is the very real tendency for those body's to move toward one another. This the a "gravity" part.
The "Force" is the product of the Mass and Acceleration (Gravity)
By the very definition, Gravity, by itself, is not and can not, be a force.
The, improper term, "Force of Gravity" should read "Force due to Gravity".
Gravity is a constituent component of force, but, by itself, is NOT a force.
Please, any engineer, or physicist on here who disagrees, pull the text you studied under and site me chapter and verse where it says otherwise. (For you others, stay away from undocumented web posting, please!)
No need to get snarky. Besides, we're all being a bit off topic here. Maybe we should all change vector back to the original topic.
Force has multiple definitions - all valid in their own contexts.
In the context of this thread (
), death suspected from blunt force trauma in a zero-g environ would avoid gravity interfering with the results, which may help in reconstructing amount and directions of force applied. This could help ascertain actual cause of death (sufficient force?) and circumstances... (victim resisting, fleeing, etc.).
In the context of this thread (
), death suspected from blunt force trauma in a zero-g environ would avoid gravity interfering with the results, which may help in reconstructing amount and directions of force applied. This could help ascertain actual cause of death (sufficient force?) and circumstances... (victim resisting, fleeing, etc.).
Vladika
SOC-14 1K
Sorry if it came across that way. It wasn't intended.
I get frustrated with the untrained "experts" though.
You obviously had the concept well understood in your post, #25, this thread.
Jeff M. Hopper
SOC-14 1K
Thank you.
No, the difference is that I directed my comments at the equations and the engineering concept. You directed your comments at other people.
Fritz_Brown
Super Moderator
Which is where we came in - death in space.
The forensics would be the same in some ways: you would examine what had happened, and it would tell you (hopefully) if someone had messed with the body since death. Query: could you strangle someone, then set them spinning so the blood would go to their brain? Thereby defying the "they died from lack of blood in the brain" reasoning?
The forensics would be the same in some ways: you would examine what had happened, and it would tell you (hopefully) if someone had messed with the body since death. Query: could you strangle someone, then set them spinning so the blood would go to their brain? Thereby defying the "they died from lack of blood in the brain" reasoning?
Which is where we came in - death in space.
The forensics would be the same in some ways: you would examine what had happened, and it would tell you (hopefully) if someone had messed with the body since death. Query: could you strangle someone, then set them spinning so the blood would go to their brain? Thereby defying the "they died from lack of blood in the brain" reasoning?
According to what I read and see on TV (I am not any kind of med professional), any strangulation leaves telltale broken blood vessels in the eyes (pettachial hemorrhages) so simply messing w blood pooling would not hide it.
(Also most strangulation breaks or damages the hyoid in a particular way, another telltale for that method of killing - although I don't think this would be the case with a blood choke that is held beyond unconsciousness until death, at least not the way we did them in judo.)
I'd think, regardless of the final disposition of the blood, the effects of deprivation of blood/oxygen to the brain would be detectable... but not really my area, so I'm just speculating.
Not necessarily in this particular situation, perhaps, but could imagine a planet bound specialist might mistake circumstances and cause of death due to the effects of micro/zero g environs...
Not necessarily in this particular situation, perhaps, but could imagine a planet bound specialist might mistake circumstances and cause of death due to the effects of micro/zero g environs...
What most strangulation would leave is haematomes on the parts of skin taht were pressed to strangulate, and this would be quite difficult to hide.
Speaking of bruising and blood pooling - without gravity I'd think the body would be more likely to bleed and bruise after death. Unless restrained or halted, physical trauma in zero-g would generally leave the body with some net motion causing impacts that could result in quite a bit of confusing blood loss or bruising after death.
Without blood pooling - the body might tend to bloat differently as well - I recall the head and upper body of astronauts tend to bloat disproportionately when they are first becoming acclimated to micro-gravity and I think to a degree after (something about the amount of water retention, IIRC?).
Timing wise perhaps this would be confused with inflammation on a casual inspection? Though tissue samples should clarify that, just as I would presume (again total layman speculation here, sure its not as easy as all that) such would be the case with most forensics that have access to the actual tissues and proper lab knowledge and equipment. From a gaming perspective, I suspect there are enough differences related to blood and physical condition to justify misdiagnosis of time and cause, at least on a cursory basis...
Without blood pooling - the body might tend to bloat differently as well - I recall the head and upper body of astronauts tend to bloat disproportionately when they are first becoming acclimated to micro-gravity and I think to a degree after (something about the amount of water retention, IIRC?).
Timing wise perhaps this would be confused with inflammation on a casual inspection? Though tissue samples should clarify that, just as I would presume (again total layman speculation here, sure its not as easy as all that) such would be the case with most forensics that have access to the actual tissues and proper lab knowledge and equipment. From a gaming perspective, I suspect there are enough differences related to blood and physical condition to justify misdiagnosis of time and cause, at least on a cursory basis...
Lycanorukke
SOC-13
A more modern technique for estimating ToD is measuring potassium levels in the virtious humor in the eyes.
When alive the amount of potassium is constant, but when dead, the cells release thier potassium which is not cleaned away. Hence they can calculate how long dead the body was by measuring the Potassium levels - they use the humor because it has a constant potassium level. A more basic overview of todays forensics can be gotten as a google book. The first chapter covers the basics what happens on death and how those methods are used for ToD.
Essential Forensic Biology.
**NOTE**. The extracts from the book do have medical photos of bodies in various stages of lividity, rigor and decomposition as well a clincial descriptions. Use link as own risk.
When alive the amount of potassium is constant, but when dead, the cells release thier potassium which is not cleaned away. Hence they can calculate how long dead the body was by measuring the Potassium levels - they use the humor because it has a constant potassium level. A more basic overview of todays forensics can be gotten as a google book. The first chapter covers the basics what happens on death and how those methods are used for ToD.
Essential Forensic Biology.
**NOTE**. The extracts from the book do have medical photos of bodies in various stages of lividity, rigor and decomposition as well a clincial descriptions. Use link as own risk.
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