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Are humans the only species in which some members are exclusively herbivorous and others aren't? Neon Merlin 00:20, 10 August 2008 (UTC)
Clearly example is pyrhana, there are 2 types seperately (omnivore and herbivore)....Ninjaw —Preceding unsigned comment added by 124.120.200.29 ( talk) 06:59, 10 August 2008 (UTC)
Also mosquitoes- the males are exclusively herbivorous and the females exclusively drink blood. Nadando ( talk) 23:51, 12 August 2008 (UTC)
i need help trakcing down sources for wet wipe markers, also known as chalk in or fluorescent markers, you know they ones they use on the outdoor menu displays at restaurants, that look like chalk but wont get all messy, yeah those. theres a bunch of alleged sources here, but i can't find them on their own, would anyone care to help? MY♥INchile 00:38, 10 August 2008 (UTC)
Water is 1 gm/cc. what is blood density? please? —Preceding unsigned comment added by 79.76.242.64 ( talk) 01:29, 10 August 2008 (UTC)
Would it be noticeable on some level? Like physical laws changing? I thought like Einstein and realized space is relative so at first I thought no. Then I remembered something- singularities. How could you double the "size" of that without seriously disrupting something? It would probably spawn some new emergent property with disastrous consequences! 0_0 ----- Sam Science ( talk) 01:38, 10 August 2008 (UTC)
What is it? —Preceding unsigned comment added by 79.76.242.64 ( talk) 02:34, 10 August 2008 (UTC)
When our "gas log" fireplace needed some troubleshooting, I measured this. If memory serves, that particular thermopile was capable of putting out about 40 mA at some very low voltage. Half the current operated the "pilot light maintaining coil" in the gas valve and the other half operated the "main burner coil" in the gas valve. I took notes; if you really need to know the details, I can probably dig them up.
Atlant ( talk) 19:30, 14 August 2008 (UTC)
Upthread, someone provided a link to a typical "large" Honeywell millivolt control valve. The specs for that valve state:
ELECTRICAL DATA: Pilotstat Power Unit - Hold-in 15 ma maximum; dropout 10.5 to 4.5 ma; resistance 11 ohms. Valve Operator - Pull-in 65 ma maximum; coil resistance 2 ohms.
And state that the millivolt thermopile produces about 750 mV open circuit.
Atlant ( talk) 21:06, 14 August 2008 (UTC)
Standard instructions for cooking spagetti (and other dry pasta) are:
bring water to a boil, then put the pasta in the boiling water.
Is there any good reason to do it this way, or will it work just as well to put the pasta into cold or warm water, then bring the water to a boil?
Based on limited experiment, I suspect the latter is the case.
Thanks, Wanderer57 ( talk) 02:54, 10 August 2008 (UTC)
If you add a little olive oil, the pasta won't stick together. AndMe2 66.52.8.89 ( talk) 03:25, 10 August 2008 (UTC)
Recently while up a ladder to cut a branch off a tree, I noticed ants on the bark of the tree.
Why might ants go to all the work of climbing trees?
The tree was not doing something that might have provided food to the ants, like flowering or dripping sap.
Thanks, Wanderer57 ( talk) 03:05, 10 August 2008 (UTC)
For example, how do they know the "smallest" planck length is 10 to the negative 20th power? Couldn't you just divide again? The problem could be scale. If something the size of the universe was trying to measure something on our scale it would be meaningless to observer.- And observed.-- Sam Science ( talk) 03:58, 10 August 2008 (UTC)
OK. The rings of Saturn were not sorted by centrifugal force. I never quite believed it anyway.
But the discussion has led me to some further thoughts about centrifugal separation.
Assume a mixture of material is being separated in a centrifuge. Is the size of the particles significant in centrifugal separation? Conventional (high school) wisdom says "No". But I am wondering why.
To illustrate, let us say a quantity of glass marbles is mixed with a quantity of steel balls. The marbles and steel balls all have the same diameter. Each steel ball therefore has a greater mass than each glass marble. The mixture is put in a large centrifuge and spun. The steel balls will more strongly resist deviation from motion in a straight line and will push their way between the marbles. The steel balls will thus work their way to the outer edge of the spin path. The inevitable vibration (from imperfect bearings, etc.) would hasten the process. A thin coat of non-sticky lubricant on each ball would also assist by reducing friction as the balls slide past each other. Or for simplicity to establish the basic principle, we could assume there is no friction between any of the balls. (Centrifugal separation of gases avoids most of the friction, I think.)
Now imagine a mixture of glass marbles and lead shot. The marbles are all the same diameter. Each lead shot is the same diameter as other lead shot, but is small enough that it has less mass than each marble. Spin the mixture in a centrifuge. The marbles (having greater mass) will more strongly resist deviation from motion in a straight line Will the marbles work their way past the lead shot to the outer edge of the spin path? If so, the materials will become separated by their density, rather than their mass. Let us assume there is no friction.
I don't have an answer to this. Maybe someone can come up with one.
Andme2 ( talk) 07:44, 10 August 2008 (UTC)
Let's try the Brazil nut effect with the marbles and lead shot. Put a mixture of them in a container and fasten the container on a shake table. Start the shaker.
There is no centrifugal force. But this shake table has a vertical component of motion. That frequently throws the marbles and lead shot upward, after which they fall downward.
This shake table also has a horizontal component of motion. As the marbles and lead shot fall downward, the shake table will exert a horizontal force that presses on the marbles and lead shot in contact with the sides of the container. These, in turn, press on some of the adjacent marbles and lead shot. Some of the lead shot will then be pushed a little way beneath some of the marbles. These marbles will rise in the mixture when all the material settles on the bottom of the container.
Some lead shot also gets pushed on top of some of the marbles during the fall. But these will tend to roll off the marbles when the entire mass comes to rest on the bottom of the container. In time, all the marbles will be on top.
By the way, the horizontal push exerted sequentially by each side of the container, together with the rising marbles, accounts for the convection current. In a cylindrical container, the horizontal push exerted sequentially to all sides of the mass is carried through the mass and meets more or less in the center of the container, where it all cancels out. (This convection current will be most noticeable when the particles are more similar in size and density.)
Now imagine the experiment is done with marbles and lead balls, with all spheres having the same diameter. The horizontal component will shove some lead balls part way beneath some marbles during the fall. But (statistically speaking) an equal number of marbles will be pushed under lead balls. There will therefore be no sorting due to horizontal motion.
To clarify the equal-diameter-spheres situation, imagine that only marbles of equal diameter are used. Some are green marbles and some are red marbles. Obviously there will be no sorting due to vertical motion followed by horizontal motion. There will be no wedging effect of small balls being pushed beneath large balls.
These thought experiments ignore the elasticity of the spheres, and permanent distortion of the lead balls that may be caused during the experiment. Air currents during the fall are also ignored. However, by weeding out extraneous elements, we can see the basic process. Extraneous elements can then be figured in later if needed.
Oh, one more thing. I said the force exerted by the shake table has a vertical component and a horizontal component. If these are exerted simultaneously in a curving manner, there will be a centrifugal force. This will be slight and has been treated as an extraneous element. But a special shake table could be built in which these forces are not exerted simultaneously.
Andme2 ( talk) 22:57, 10 August 2008 (UTC)
Greetings.
We have a stand of rather tall Eucalyptas tree in our yard.
We live in Carmel Valley,Ca
Just recently r deck in the back by the stand is getting bombed with PURPLE droppings,,looks like bird poooooooop, but it is a berry color..!!!
Not trying to stop it, just would like to know what the heck is really going on,,?
Regards.............and................Thanks -- Ddemos ( talk) 09:04, 10 August 2008 (UTC)
As I understand, flu like symptoms are a reaction of the body to a pathogen which arise in the process of immune defense. But how exactly are these symptoms (or what immediately causes them) helping to defend the pathogen? 93.132.159.115 ( talk) 10:56, 10 August 2008 (UTC)
What are the references to mdern physics in the movie The Matrix ? 69.157.227.243 ( talk) 13:40, 10 August 2008 (UTC)
Do animals get zits? If they do can they squeeze them? —Preceding unsigned comment added by 86.128.192.207 ( talk) 17:15, 10 August 2008 (UTC)
Do animals have umbilical cords? If so, what do wild animals do with them? Humans usually cut them and tie them up, but of course animals can't do the tying, so what happens? I am just thinking this, because they must have them, otherwise the foetus would not be able to feed inside the mother. I've seen calves getting born, and they just seem to 'fall out', so to speak, totally unattached. Does it just come off inside the mother? If so, why is a human umbilical so long?-- ChokinBako ( talk) 17:44, 10 August 2008 (UTC)
I bought some bismuth tin alloy in the form of shot for some magnet experiments. i was expecting it to be strongly diamagnetic, but I dont get any effect with NIB magnets brought close to it. Is Bismuth tin (the alloy) diamagnetic, of does it have to be pure bismuth? —Preceding unsigned comment added by 79.76.242.64 ( talk) 20:34, 10 August 2008 (UTC)
{{
cite journal}}
: Check date values in: |date=
(
help)) and the relationship of the ratio of the two metals in alloy to the magnetic susceptibility of the alloy is not simple at all. Not all ratios of the two metals given a magnetic alloy (and even the sign of the magnetic susceptibility changes!).
DMacks (
talk)
05:01, 11 August 2008 (UTC)Science desk | ||
---|---|---|
< August 9 | << Jul | August | Sep >> | August 11 > |
Welcome to the Wikipedia Science Reference Desk Archives |
---|
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
Are humans the only species in which some members are exclusively herbivorous and others aren't? Neon Merlin 00:20, 10 August 2008 (UTC)
Clearly example is pyrhana, there are 2 types seperately (omnivore and herbivore)....Ninjaw —Preceding unsigned comment added by 124.120.200.29 ( talk) 06:59, 10 August 2008 (UTC)
Also mosquitoes- the males are exclusively herbivorous and the females exclusively drink blood. Nadando ( talk) 23:51, 12 August 2008 (UTC)
i need help trakcing down sources for wet wipe markers, also known as chalk in or fluorescent markers, you know they ones they use on the outdoor menu displays at restaurants, that look like chalk but wont get all messy, yeah those. theres a bunch of alleged sources here, but i can't find them on their own, would anyone care to help? MY♥INchile 00:38, 10 August 2008 (UTC)
Water is 1 gm/cc. what is blood density? please? —Preceding unsigned comment added by 79.76.242.64 ( talk) 01:29, 10 August 2008 (UTC)
Would it be noticeable on some level? Like physical laws changing? I thought like Einstein and realized space is relative so at first I thought no. Then I remembered something- singularities. How could you double the "size" of that without seriously disrupting something? It would probably spawn some new emergent property with disastrous consequences! 0_0 ----- Sam Science ( talk) 01:38, 10 August 2008 (UTC)
What is it? —Preceding unsigned comment added by 79.76.242.64 ( talk) 02:34, 10 August 2008 (UTC)
When our "gas log" fireplace needed some troubleshooting, I measured this. If memory serves, that particular thermopile was capable of putting out about 40 mA at some very low voltage. Half the current operated the "pilot light maintaining coil" in the gas valve and the other half operated the "main burner coil" in the gas valve. I took notes; if you really need to know the details, I can probably dig them up.
Atlant ( talk) 19:30, 14 August 2008 (UTC)
Upthread, someone provided a link to a typical "large" Honeywell millivolt control valve. The specs for that valve state:
ELECTRICAL DATA: Pilotstat Power Unit - Hold-in 15 ma maximum; dropout 10.5 to 4.5 ma; resistance 11 ohms. Valve Operator - Pull-in 65 ma maximum; coil resistance 2 ohms.
And state that the millivolt thermopile produces about 750 mV open circuit.
Atlant ( talk) 21:06, 14 August 2008 (UTC)
Standard instructions for cooking spagetti (and other dry pasta) are:
bring water to a boil, then put the pasta in the boiling water.
Is there any good reason to do it this way, or will it work just as well to put the pasta into cold or warm water, then bring the water to a boil?
Based on limited experiment, I suspect the latter is the case.
Thanks, Wanderer57 ( talk) 02:54, 10 August 2008 (UTC)
If you add a little olive oil, the pasta won't stick together. AndMe2 66.52.8.89 ( talk) 03:25, 10 August 2008 (UTC)
Recently while up a ladder to cut a branch off a tree, I noticed ants on the bark of the tree.
Why might ants go to all the work of climbing trees?
The tree was not doing something that might have provided food to the ants, like flowering or dripping sap.
Thanks, Wanderer57 ( talk) 03:05, 10 August 2008 (UTC)
For example, how do they know the "smallest" planck length is 10 to the negative 20th power? Couldn't you just divide again? The problem could be scale. If something the size of the universe was trying to measure something on our scale it would be meaningless to observer.- And observed.-- Sam Science ( talk) 03:58, 10 August 2008 (UTC)
OK. The rings of Saturn were not sorted by centrifugal force. I never quite believed it anyway.
But the discussion has led me to some further thoughts about centrifugal separation.
Assume a mixture of material is being separated in a centrifuge. Is the size of the particles significant in centrifugal separation? Conventional (high school) wisdom says "No". But I am wondering why.
To illustrate, let us say a quantity of glass marbles is mixed with a quantity of steel balls. The marbles and steel balls all have the same diameter. Each steel ball therefore has a greater mass than each glass marble. The mixture is put in a large centrifuge and spun. The steel balls will more strongly resist deviation from motion in a straight line and will push their way between the marbles. The steel balls will thus work their way to the outer edge of the spin path. The inevitable vibration (from imperfect bearings, etc.) would hasten the process. A thin coat of non-sticky lubricant on each ball would also assist by reducing friction as the balls slide past each other. Or for simplicity to establish the basic principle, we could assume there is no friction between any of the balls. (Centrifugal separation of gases avoids most of the friction, I think.)
Now imagine a mixture of glass marbles and lead shot. The marbles are all the same diameter. Each lead shot is the same diameter as other lead shot, but is small enough that it has less mass than each marble. Spin the mixture in a centrifuge. The marbles (having greater mass) will more strongly resist deviation from motion in a straight line Will the marbles work their way past the lead shot to the outer edge of the spin path? If so, the materials will become separated by their density, rather than their mass. Let us assume there is no friction.
I don't have an answer to this. Maybe someone can come up with one.
Andme2 ( talk) 07:44, 10 August 2008 (UTC)
Let's try the Brazil nut effect with the marbles and lead shot. Put a mixture of them in a container and fasten the container on a shake table. Start the shaker.
There is no centrifugal force. But this shake table has a vertical component of motion. That frequently throws the marbles and lead shot upward, after which they fall downward.
This shake table also has a horizontal component of motion. As the marbles and lead shot fall downward, the shake table will exert a horizontal force that presses on the marbles and lead shot in contact with the sides of the container. These, in turn, press on some of the adjacent marbles and lead shot. Some of the lead shot will then be pushed a little way beneath some of the marbles. These marbles will rise in the mixture when all the material settles on the bottom of the container.
Some lead shot also gets pushed on top of some of the marbles during the fall. But these will tend to roll off the marbles when the entire mass comes to rest on the bottom of the container. In time, all the marbles will be on top.
By the way, the horizontal push exerted sequentially by each side of the container, together with the rising marbles, accounts for the convection current. In a cylindrical container, the horizontal push exerted sequentially to all sides of the mass is carried through the mass and meets more or less in the center of the container, where it all cancels out. (This convection current will be most noticeable when the particles are more similar in size and density.)
Now imagine the experiment is done with marbles and lead balls, with all spheres having the same diameter. The horizontal component will shove some lead balls part way beneath some marbles during the fall. But (statistically speaking) an equal number of marbles will be pushed under lead balls. There will therefore be no sorting due to horizontal motion.
To clarify the equal-diameter-spheres situation, imagine that only marbles of equal diameter are used. Some are green marbles and some are red marbles. Obviously there will be no sorting due to vertical motion followed by horizontal motion. There will be no wedging effect of small balls being pushed beneath large balls.
These thought experiments ignore the elasticity of the spheres, and permanent distortion of the lead balls that may be caused during the experiment. Air currents during the fall are also ignored. However, by weeding out extraneous elements, we can see the basic process. Extraneous elements can then be figured in later if needed.
Oh, one more thing. I said the force exerted by the shake table has a vertical component and a horizontal component. If these are exerted simultaneously in a curving manner, there will be a centrifugal force. This will be slight and has been treated as an extraneous element. But a special shake table could be built in which these forces are not exerted simultaneously.
Andme2 ( talk) 22:57, 10 August 2008 (UTC)
Greetings.
We have a stand of rather tall Eucalyptas tree in our yard.
We live in Carmel Valley,Ca
Just recently r deck in the back by the stand is getting bombed with PURPLE droppings,,looks like bird poooooooop, but it is a berry color..!!!
Not trying to stop it, just would like to know what the heck is really going on,,?
Regards.............and................Thanks -- Ddemos ( talk) 09:04, 10 August 2008 (UTC)
As I understand, flu like symptoms are a reaction of the body to a pathogen which arise in the process of immune defense. But how exactly are these symptoms (or what immediately causes them) helping to defend the pathogen? 93.132.159.115 ( talk) 10:56, 10 August 2008 (UTC)
What are the references to mdern physics in the movie The Matrix ? 69.157.227.243 ( talk) 13:40, 10 August 2008 (UTC)
Do animals get zits? If they do can they squeeze them? —Preceding unsigned comment added by 86.128.192.207 ( talk) 17:15, 10 August 2008 (UTC)
Do animals have umbilical cords? If so, what do wild animals do with them? Humans usually cut them and tie them up, but of course animals can't do the tying, so what happens? I am just thinking this, because they must have them, otherwise the foetus would not be able to feed inside the mother. I've seen calves getting born, and they just seem to 'fall out', so to speak, totally unattached. Does it just come off inside the mother? If so, why is a human umbilical so long?-- ChokinBako ( talk) 17:44, 10 August 2008 (UTC)
I bought some bismuth tin alloy in the form of shot for some magnet experiments. i was expecting it to be strongly diamagnetic, but I dont get any effect with NIB magnets brought close to it. Is Bismuth tin (the alloy) diamagnetic, of does it have to be pure bismuth? —Preceding unsigned comment added by 79.76.242.64 ( talk) 20:34, 10 August 2008 (UTC)
{{
cite journal}}
: Check date values in: |date=
(
help)) and the relationship of the ratio of the two metals in alloy to the magnetic susceptibility of the alloy is not simple at all. Not all ratios of the two metals given a magnetic alloy (and even the sign of the magnetic susceptibility changes!).
DMacks (
talk)
05:01, 11 August 2008 (UTC)