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If an electric motor was allowed to run while floating free in space, then presumably the armature would rotate one way and the casing the other, but at what relative speeds? I'm guessing there must be an equation relating the two rotational speeds, that somehow also involves the masses of the components. For example if the casing was very heavy compared to the armature then it it seems intuitive that it would rotate more slowly. But what exactly would that equation be? 86.177.105.243 ( talk) 00:05, 22 May 2012 (UTC)
_ / \ | _ | -----____ | ----------- | --------------------------- \______________ -----------
How does gravitational time dilation operate at the centre of a large mass (not a black hole though)? Does gravity affect time when it pulls in all directions? And on a related note, what time dilation effects would happen if you have a clock in between two massive objects, and is therefore pulled in two opposing directions (equally, and let's pretend the two objects will not fall into each other)? Would the opposing gravitational fields cancel out the effects of time-dilation on the clock or would the two sum together? 137.111.13.167 ( talk) 02:49, 22 May 2012 (UTC)
A normal Racing pigeon has ten primary flight feathers in each wing. There is, however, an uncommon gene that duplicates the second primary flight feather. This can be seen here. Compare that to the regular, 10-flighted bird seen here.
You'll notice the first few flight feathers of the regular bird are separated at their tips, however this is not the case in the bird with the duplicated second flight feather.
What do you think will be the impact on flight efficiency and speed caused by the extra flight feather? Will the bird fly more efficiently due to the extra feather, or less efficiently due to the lack of a gap? Or another reason?
Thanks, Abbott75
I hope this is not an inappropriate question for the Science Desk, but there are so many smart people here I'd love to see the answers. Delete this question if necessary.
I was thinking this morning about "Whoa!" moments; the moments when you learn a new fact that rocks your world. Two for me I could think of right off were: 1) When I learned every bit of me used to be inside a star; and 2) When I learned the "double slit" experiment worked with only one electron.
What were your "Whoa!" moments? Tdjewell ( talk) 11:29, 22 May 2012 (UTC)
Many such moments. I learned a lot about science in primary school myself from books, and I realized that religion had to be nonsense despite many grown up people telling stories about the Bible and God as if it were fact. So, the first (and I guess most important) whoa moment was that you could actually not trust grown ups to know the facts even on points they were very sure about.
But I get whoa moments almost every week when I read about some intneresting facts. E.g. just last weeks on a t.v. documentary about the evolution of plants, it was mentioned that grass evolved in such a way as to be able to start fires that would destroy trees, making more room for them. Also, I found out rather late in my life that many vegetables didn't exist more than a few thousand years ago, being the result of selective breeding. Count Iblis ( talk) 18:04, 23 May 2012 (UTC)
Here (youtube link) is an example of a turtle heart that keeps on beating half an hour after the turtle died - and a few minutes after being cut out of the body.
What are other examples of zombie body parts that just keep on going? Are there any human examples? Egg Centri c 11:44, 22 May 2012 (UTC)
What sort of chemicals would cause these problems? Hcobb ( talk) 15:47, 22 May 2012 (UTC)
The F-35's stealth is "baked in" rather than "splatted on", but I've yet to find a RS that points out that this means that stealth goo sickness won't be a problem with the F-35. So far all my sources say that either the F-22's stealth goo is so harmless that you could use it as a dessert topping to feed to your kids or pieces like this that paint all stealth platforms with the same toxic goo brush:
http://www.phibetaiota.net/winslow-wheeler-the-f-22-toxic-stealth-secrets-screw-sick/
Hcobb ( talk) 16:07, 25 May 2012 (UTC)
The National Weather Service in Tuscon has issued a Red Flag Warning for my area. I was reading the warning and had a question about some terminology used within:
.LOW PRESSURE PASSING NORTH OF ARIZONA WILL CREATE STRONG AND GUSTY WINDS ON WEDNESDAY...WITH SUSTAINED 20-FOOT WIND SPEEDS UP TO 30 MPH AND GUSTS TO NEAR 50 MPH. THESE WINDS...COUPLED WITH CONTINUED HOT AND DRY CONDITIONS...WILL CREATE CRITICAL FIRE WEATHER CONDITIONS THAT MAY RESULT IN RAPID FIRE GROWTH AND SPREAD. ... * WINDS...SUSTAINED 20-FOOT SOUTHWEST WINDS OF 25 TO 35 MPH ARE EXPECTED WITH GUSTS TO NEAR 50 MPH. THE STRONGEST WINDS ARE EXPECTED IN EASTERN PORTIONS OF THE WARNED AREA.
The warning is archived here.
What does "20-foot winds" mean? Thanks! -- 143.85.199.242 ( talk) 17:53, 22 May 2012 (UTC)
I've read that according to the sunscreen controversy that many sunscreens contain avobenzone and octocrylene which absorb into the skin and are potent free radical generators. I would certainly like to avoid this kind of thing while protecting my skin. Where can I find waterproof sunscreens that judiciously prefer to use titanium dioxide or zinc oxide as stabilisers rather than octocrylene, as well as other dangerous ingredients? 137.54.7.13 ( talk) 18:24, 22 May 2012 (UTC)
I have noticed that on the Gravitational Redshift Page there exists an equation for calculating gravitational redshift. There is no Equation on their for calculating Gravitational Blueshift, there is no Gravitational Blueshift Page, and there is a Blueshift page, but it also lacks an equation for calculating Gravitational Blueshift. The Equation:
I also failed to locate such a blueshift equation anywhere else on the internet. So I then tried to figure it out on my own. I went about this by plugging variables into the redshift equation and then attempting to discern the blueshift one through the results. I am not entirely sure I did this correctly. Please tell me if I didn't.
First off the variables:
R* = 5m
r = 10m
M = 1x1027kg
G (used the compatible one) = 6.673848x10-11 N (m/kg)2
c (not sure if this is the compatible version) = 3x108m/s
λI = 100m
So I solved it step by step:
2GM: 2 x G x (1x1027) = 1.3347696x1017
R*c2: 5 x (3x108)2 = 4.5x1017
2GM/R*c2: 1.3347696x1017 / 4.5x1017 = .296615467
1 - 2GM/R*c2: 1 - .296615467 = .703384533
Square Root of 1 - 2GM/R*c2: Square Root of .703384533 = .838680233
1/(Square Root of 1 - 2GM/R*c2): 1 / .838680233 = 1.192349552
1/(Square Root of 1 - 2GM/R*c2) - 1: .192349552
z(r) = 1/(Square Root of 1 - 2GM/R*c2) - 1 --> z = [1/(Square Root of 1 - 2GM/R*c2) - 1]/r:
z(10) = .192349552 --> z = .192349552 / 10 = .0192349552
Now as the page said z is a fractional change of the wavelength, I came up with this equation:
λF = λI - (λIz)
When plugging this in I got: λF = 98.07650448
Now to figure out the Blueshift Equation I figured I had to keep the same variables (except R* and r swap values, since R* "is the radial coordinate of the point of emission (which is analogous to the classical distance from the center of the object, but is actually a Schwarzschild coordinate)." And r is "the radial coordinate of the observer").
I came up with the equation one would need after one figures out z:
λF = λI + (λIz) Which in this case would be: 100 = 98.07650448 + (98.07650448z) Because for the sake of Energy Conservation the amount of potential gravitational blueshift must be equivalent to the potential gravitational redshift and so 98.07650448m would have to return to being 100m.
I then calculated what z would have to equal for such a thing to happen through these steps:
λF - λI = Required Increase: 100 - 98.07650448 = 1.92349552
Required Increase/λI = z: 1.92349552 / 98.07650448 = .019612195
And so, I arrived at z = .019612195
I even plugged it in to the equation to be sure:
λF = λI + (λI x z): 98.07650448 + (98.07650448 x .019612195) = 100
I then could not figure out a Gravitational Blueshift Equation that yielded said z value. I found many incorrect solutions. In fact, I even tried plugging into the Gravitational Redshift Equation (which I knew would not work) in desperation.
Could someone who is more experienced with this sort of calculations please help? Some of the problems I have been working on simply require a Gravitational Blueshift Equation.
Doctor Condensate ( talk) 22:46, 22 May 2012 (UTC)
Thank you for the quick responses. Well, BenRG. My current work requires the following. First, an equation that calculates the redshift of light emitted from a point at a specific distance from the center of a spherical object with mass, and observed at a point directly above the point of emission (which of course is also at a specific distance from the center).
Second, I need an equation that calculates the inverse. I need to be able to calculate the blueshift of light emitted from a point at a specific distance from the center of a spherical object with mass, and observed at a point directly below it. Which, I think Icek provided for me.
For both of these, a line that passes through both the point of emission and the point of observation should also pass directly though the center of the spherical object with mass.
Doctor Condensate ( talk) 00:16, 24 May 2012 (UTC)
Okay, thank you very much.
Science desk | ||
---|---|---|
< May 21 | << Apr | May | Jun >> | May 23 > |
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. |
If an electric motor was allowed to run while floating free in space, then presumably the armature would rotate one way and the casing the other, but at what relative speeds? I'm guessing there must be an equation relating the two rotational speeds, that somehow also involves the masses of the components. For example if the casing was very heavy compared to the armature then it it seems intuitive that it would rotate more slowly. But what exactly would that equation be? 86.177.105.243 ( talk) 00:05, 22 May 2012 (UTC)
_ / \ | _ | -----____ | ----------- | --------------------------- \______________ -----------
How does gravitational time dilation operate at the centre of a large mass (not a black hole though)? Does gravity affect time when it pulls in all directions? And on a related note, what time dilation effects would happen if you have a clock in between two massive objects, and is therefore pulled in two opposing directions (equally, and let's pretend the two objects will not fall into each other)? Would the opposing gravitational fields cancel out the effects of time-dilation on the clock or would the two sum together? 137.111.13.167 ( talk) 02:49, 22 May 2012 (UTC)
A normal Racing pigeon has ten primary flight feathers in each wing. There is, however, an uncommon gene that duplicates the second primary flight feather. This can be seen here. Compare that to the regular, 10-flighted bird seen here.
You'll notice the first few flight feathers of the regular bird are separated at their tips, however this is not the case in the bird with the duplicated second flight feather.
What do you think will be the impact on flight efficiency and speed caused by the extra flight feather? Will the bird fly more efficiently due to the extra feather, or less efficiently due to the lack of a gap? Or another reason?
Thanks, Abbott75
I hope this is not an inappropriate question for the Science Desk, but there are so many smart people here I'd love to see the answers. Delete this question if necessary.
I was thinking this morning about "Whoa!" moments; the moments when you learn a new fact that rocks your world. Two for me I could think of right off were: 1) When I learned every bit of me used to be inside a star; and 2) When I learned the "double slit" experiment worked with only one electron.
What were your "Whoa!" moments? Tdjewell ( talk) 11:29, 22 May 2012 (UTC)
Many such moments. I learned a lot about science in primary school myself from books, and I realized that religion had to be nonsense despite many grown up people telling stories about the Bible and God as if it were fact. So, the first (and I guess most important) whoa moment was that you could actually not trust grown ups to know the facts even on points they were very sure about.
But I get whoa moments almost every week when I read about some intneresting facts. E.g. just last weeks on a t.v. documentary about the evolution of plants, it was mentioned that grass evolved in such a way as to be able to start fires that would destroy trees, making more room for them. Also, I found out rather late in my life that many vegetables didn't exist more than a few thousand years ago, being the result of selective breeding. Count Iblis ( talk) 18:04, 23 May 2012 (UTC)
Here (youtube link) is an example of a turtle heart that keeps on beating half an hour after the turtle died - and a few minutes after being cut out of the body.
What are other examples of zombie body parts that just keep on going? Are there any human examples? Egg Centri c 11:44, 22 May 2012 (UTC)
What sort of chemicals would cause these problems? Hcobb ( talk) 15:47, 22 May 2012 (UTC)
The F-35's stealth is "baked in" rather than "splatted on", but I've yet to find a RS that points out that this means that stealth goo sickness won't be a problem with the F-35. So far all my sources say that either the F-22's stealth goo is so harmless that you could use it as a dessert topping to feed to your kids or pieces like this that paint all stealth platforms with the same toxic goo brush:
http://www.phibetaiota.net/winslow-wheeler-the-f-22-toxic-stealth-secrets-screw-sick/
Hcobb ( talk) 16:07, 25 May 2012 (UTC)
The National Weather Service in Tuscon has issued a Red Flag Warning for my area. I was reading the warning and had a question about some terminology used within:
.LOW PRESSURE PASSING NORTH OF ARIZONA WILL CREATE STRONG AND GUSTY WINDS ON WEDNESDAY...WITH SUSTAINED 20-FOOT WIND SPEEDS UP TO 30 MPH AND GUSTS TO NEAR 50 MPH. THESE WINDS...COUPLED WITH CONTINUED HOT AND DRY CONDITIONS...WILL CREATE CRITICAL FIRE WEATHER CONDITIONS THAT MAY RESULT IN RAPID FIRE GROWTH AND SPREAD. ... * WINDS...SUSTAINED 20-FOOT SOUTHWEST WINDS OF 25 TO 35 MPH ARE EXPECTED WITH GUSTS TO NEAR 50 MPH. THE STRONGEST WINDS ARE EXPECTED IN EASTERN PORTIONS OF THE WARNED AREA.
The warning is archived here.
What does "20-foot winds" mean? Thanks! -- 143.85.199.242 ( talk) 17:53, 22 May 2012 (UTC)
I've read that according to the sunscreen controversy that many sunscreens contain avobenzone and octocrylene which absorb into the skin and are potent free radical generators. I would certainly like to avoid this kind of thing while protecting my skin. Where can I find waterproof sunscreens that judiciously prefer to use titanium dioxide or zinc oxide as stabilisers rather than octocrylene, as well as other dangerous ingredients? 137.54.7.13 ( talk) 18:24, 22 May 2012 (UTC)
I have noticed that on the Gravitational Redshift Page there exists an equation for calculating gravitational redshift. There is no Equation on their for calculating Gravitational Blueshift, there is no Gravitational Blueshift Page, and there is a Blueshift page, but it also lacks an equation for calculating Gravitational Blueshift. The Equation:
I also failed to locate such a blueshift equation anywhere else on the internet. So I then tried to figure it out on my own. I went about this by plugging variables into the redshift equation and then attempting to discern the blueshift one through the results. I am not entirely sure I did this correctly. Please tell me if I didn't.
First off the variables:
R* = 5m
r = 10m
M = 1x1027kg
G (used the compatible one) = 6.673848x10-11 N (m/kg)2
c (not sure if this is the compatible version) = 3x108m/s
λI = 100m
So I solved it step by step:
2GM: 2 x G x (1x1027) = 1.3347696x1017
R*c2: 5 x (3x108)2 = 4.5x1017
2GM/R*c2: 1.3347696x1017 / 4.5x1017 = .296615467
1 - 2GM/R*c2: 1 - .296615467 = .703384533
Square Root of 1 - 2GM/R*c2: Square Root of .703384533 = .838680233
1/(Square Root of 1 - 2GM/R*c2): 1 / .838680233 = 1.192349552
1/(Square Root of 1 - 2GM/R*c2) - 1: .192349552
z(r) = 1/(Square Root of 1 - 2GM/R*c2) - 1 --> z = [1/(Square Root of 1 - 2GM/R*c2) - 1]/r:
z(10) = .192349552 --> z = .192349552 / 10 = .0192349552
Now as the page said z is a fractional change of the wavelength, I came up with this equation:
λF = λI - (λIz)
When plugging this in I got: λF = 98.07650448
Now to figure out the Blueshift Equation I figured I had to keep the same variables (except R* and r swap values, since R* "is the radial coordinate of the point of emission (which is analogous to the classical distance from the center of the object, but is actually a Schwarzschild coordinate)." And r is "the radial coordinate of the observer").
I came up with the equation one would need after one figures out z:
λF = λI + (λIz) Which in this case would be: 100 = 98.07650448 + (98.07650448z) Because for the sake of Energy Conservation the amount of potential gravitational blueshift must be equivalent to the potential gravitational redshift and so 98.07650448m would have to return to being 100m.
I then calculated what z would have to equal for such a thing to happen through these steps:
λF - λI = Required Increase: 100 - 98.07650448 = 1.92349552
Required Increase/λI = z: 1.92349552 / 98.07650448 = .019612195
And so, I arrived at z = .019612195
I even plugged it in to the equation to be sure:
λF = λI + (λI x z): 98.07650448 + (98.07650448 x .019612195) = 100
I then could not figure out a Gravitational Blueshift Equation that yielded said z value. I found many incorrect solutions. In fact, I even tried plugging into the Gravitational Redshift Equation (which I knew would not work) in desperation.
Could someone who is more experienced with this sort of calculations please help? Some of the problems I have been working on simply require a Gravitational Blueshift Equation.
Doctor Condensate ( talk) 22:46, 22 May 2012 (UTC)
Thank you for the quick responses. Well, BenRG. My current work requires the following. First, an equation that calculates the redshift of light emitted from a point at a specific distance from the center of a spherical object with mass, and observed at a point directly above the point of emission (which of course is also at a specific distance from the center).
Second, I need an equation that calculates the inverse. I need to be able to calculate the blueshift of light emitted from a point at a specific distance from the center of a spherical object with mass, and observed at a point directly below it. Which, I think Icek provided for me.
For both of these, a line that passes through both the point of emission and the point of observation should also pass directly though the center of the spherical object with mass.
Doctor Condensate ( talk) 00:16, 24 May 2012 (UTC)
Okay, thank you very much.