Science desk | ||
---|---|---|
< April 19 | << Mar | April | May >> | April 21 > |
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. |
Hi, Thanks everyone for your help. What we were after was what animals can jump the furthest distance (not in relation to their size or weight,) but just the longest distance.Cheers M and Z
We wanted a list of animals that can jump the furthest in asending order. Thanks Max and Zoe
This discussion reminds me of [2] which had a whole bunch of things like this Nil Einne ( talk) 15:52, 20 April 2008 (UTC)
It would be easier to color blinds to perceive them. Mr.K. (talk) 08:50, 20 April 2008 (UTC)
As noted, in a few places different shapes are used. But the color of a light can be distinguished (by people with normal vision) from a lot greater distance than its shape. So if there are drivers who have to rely on the shape, the fact that they can't see it until they're close to the intersection creates a problem anyway. So really there's little advantage in making the change, and it's cheaper for all the color lenses to be the same shape.
(But here's an interesting point: in recent years color-filtered incandescent lights have begun to be superseded in traffic lights by clusters of LEDs, which are more efficient, and more strongly colored, and longer-lasting as well. I wonder if this design change would also change the economics enough to make it practical for different shapes to be introduced with no downside. Clearly a cluster of 60 or so LEDs can be made in a squarish shape as easily as a roundish one, as long as the exact number of LEDs used is not critical.)
--Anonymous, 19:18 UTC, April 20/08.
The position of the light (top-middle-bottom) is much easier to distinguish than the shape. Therefore we do not need a shape discriminator. If we ever decide to use a single light instead of three lights, We can shift to the time domain: steady light means "STOP." Slow blink means "GO". fast blink means "Caution." no lignt at all means "this signal is broken: treat as a four-way stop." - 70.177.166.200 ( talk) 23:41, 20 April 2008 (UTC)
In Magnetoencephalography it says: "Whereas scalp EEG is sensitive to both tangential and radial components of a current source in a spherical volume conductor, MEG detects only its tangential components." Could anyone explain to me what is meant by the tangential and radial components of a current source. I had no physics at school after the age of 14, so I would prefer a rather elementary explanation. Thank you! Lova Falk ( talk) 09:12, 20 April 2008 (UTC)
If a compound has both a ketone and an aldehyde functional group which one do you use to name it? thanks Qcsaets ( talk) 12:07, 20 April 2008 (UTC)
Forget that- understand now. Thanks Qcsaets ( talk) 17:06, 20 April 2008 (UTC)
Less expensive solar cells are known for their low efficiency (less than 10% or even worse). Does it mean solar cells generate much more heat than electricity? If your roof is made of ordinary tiles, then you installed solar cells on your roof, would the solar cells actually heat up your roof and make your house hotter and cost you more in air condictioning in the summer?
Some scientists believe that in a few decades, dirt cheap solar "paints" would be available for ubiquitous solar energy conversion. You paint solar cells to the building's exterior then enjoy the free energy. Would it be the "hottest" solution to our energy crisis?
Can we circulate water under solar cells so the heat generated by the solar cells can provide you with cheap hot water? -- Toytoy ( talk) 12:20, 20 April 2008 (UTC)
Solar cells are usually mounted above the roof rather that directly on the roof, becaus most roofs are not steep enough or ar not oriented due south. Therefore, almost all of the heat is moved away by convection on h efromt and back side of the panels. The actual roof is shaded by the panels, which decreases the heat input. Even if you do not have solar cells, you could make you r attic a lot cooler by mounting panels above the roof with lots of air flow below the panels. This is not common practice because ti's a lot cheaper to ventilate the attic.If your attic is hot in the summer, you should ventilate it regardless of whether or no you have solar cells on your roof. - 70.177.166.200 ( talk) 23:18, 20 April 2008 (UTC)
Extra heat is bad in the summer but good in the winter. A theoretically ideal rooftop installation will combine electricity generation with heat management, capturing the heat in the winter, and dissipating it in the summer or using the heat for low-power-density applications like heat-powered cooling. Residential solar is costliest power in terms of injuries per watt, because a single installation does not generate very many watts, while residential rooftop work results in a lot of injuries. Therefore, it better to implement a combined system with both solar calls and solar-thermal collectiohn, because the same number of tripr to the roof will result in more overall power. - 70.177.166.200 ( talk) 23:31, 20 April 2008 (UTC)
“ | Residential solar is costliest power in terms of injuries per watt, because a single installation does not generate very many watts, while residential rooftop work results in a lot of injuries citation needed. | ” |
When the wind blows, why do leaves travel in a circular motion?
24.197.166.190 ( talk) 16:14, 20 April 2008 (UTC)XYZ
What is the world's oldest tree? 99.226.39.245 ( talk) 17:34, 20 April 2008 (UTC)
Currently, the oldest (acknowledged) living organism known is a bristlecone pine tree nicknamed "Methuselah" (after Methuselah, the longest-lived person in the Bible), located in the Ancient Bristlecone Pine Forest in the White Mountains of eastern California, and measured by core samples to be 4,789 years old.
Swedish researchers found a spruce in Dalarna that has been dated to just under 10,000 years old
A cluster of Norway Spruce in Sweden includes roots that have been carbon dated to 9,550 years old, which would make them the oldest known trees in the world. Individual trunks only last up to about 600 years, but the roots from which they grow have survived throughout the entire period.
the Bristlecone Pine called Prometheus was a little older still, 4,844 years, when it was cut down in 1964.
Zrs 12 ( talk) 17:47, 20 April 2008 (UTC)
This article is confusing in that I'm not sure if it's one tree or just a few trees with the same genetic makup, the oldest of which has died. Perhaps it's the same as Pando, which would make pando the oldest tree. 99.226.39.245 ( talk) 17:56, 20 April 2008 (UTC)
What is the advantage of using radians as opposed to degrees? Zrs 12 ( talk) 19:09, 20 April 2008 (UTC)
Alright so here's another question:
This quote is from [3] "In other words, although M and B have never been in contact, B has been imprinted with M's polarization value, across the whole galaxy, instantaneously.
This does not mean that faster-than-light information transfer has occurred."
How are these two sentences not contradictory (The article says they're not but never explains)? Zrs 12 ( talk) 19:37, 20 April 2008 (UTC)
In the cAMP signal transduction system, a hormone detected outside a cell causes the activation of adenylyl cyclase within the cell, which produces cAMP, which in turn activates a protein kinase chain. It seems that this setup loses the information about what the initial hormone is - why don't all of the different hormones that work by the cAMP system cause exactly the same effects in every cell? -- Iaerhoiee ( talk) 19:54, 20 April 2008 (UTC)
Science desk | ||
---|---|---|
< April 19 | << Mar | April | May >> | April 21 > |
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. |
Hi, Thanks everyone for your help. What we were after was what animals can jump the furthest distance (not in relation to their size or weight,) but just the longest distance.Cheers M and Z
We wanted a list of animals that can jump the furthest in asending order. Thanks Max and Zoe
This discussion reminds me of [2] which had a whole bunch of things like this Nil Einne ( talk) 15:52, 20 April 2008 (UTC)
It would be easier to color blinds to perceive them. Mr.K. (talk) 08:50, 20 April 2008 (UTC)
As noted, in a few places different shapes are used. But the color of a light can be distinguished (by people with normal vision) from a lot greater distance than its shape. So if there are drivers who have to rely on the shape, the fact that they can't see it until they're close to the intersection creates a problem anyway. So really there's little advantage in making the change, and it's cheaper for all the color lenses to be the same shape.
(But here's an interesting point: in recent years color-filtered incandescent lights have begun to be superseded in traffic lights by clusters of LEDs, which are more efficient, and more strongly colored, and longer-lasting as well. I wonder if this design change would also change the economics enough to make it practical for different shapes to be introduced with no downside. Clearly a cluster of 60 or so LEDs can be made in a squarish shape as easily as a roundish one, as long as the exact number of LEDs used is not critical.)
--Anonymous, 19:18 UTC, April 20/08.
The position of the light (top-middle-bottom) is much easier to distinguish than the shape. Therefore we do not need a shape discriminator. If we ever decide to use a single light instead of three lights, We can shift to the time domain: steady light means "STOP." Slow blink means "GO". fast blink means "Caution." no lignt at all means "this signal is broken: treat as a four-way stop." - 70.177.166.200 ( talk) 23:41, 20 April 2008 (UTC)
In Magnetoencephalography it says: "Whereas scalp EEG is sensitive to both tangential and radial components of a current source in a spherical volume conductor, MEG detects only its tangential components." Could anyone explain to me what is meant by the tangential and radial components of a current source. I had no physics at school after the age of 14, so I would prefer a rather elementary explanation. Thank you! Lova Falk ( talk) 09:12, 20 April 2008 (UTC)
If a compound has both a ketone and an aldehyde functional group which one do you use to name it? thanks Qcsaets ( talk) 12:07, 20 April 2008 (UTC)
Forget that- understand now. Thanks Qcsaets ( talk) 17:06, 20 April 2008 (UTC)
Less expensive solar cells are known for their low efficiency (less than 10% or even worse). Does it mean solar cells generate much more heat than electricity? If your roof is made of ordinary tiles, then you installed solar cells on your roof, would the solar cells actually heat up your roof and make your house hotter and cost you more in air condictioning in the summer?
Some scientists believe that in a few decades, dirt cheap solar "paints" would be available for ubiquitous solar energy conversion. You paint solar cells to the building's exterior then enjoy the free energy. Would it be the "hottest" solution to our energy crisis?
Can we circulate water under solar cells so the heat generated by the solar cells can provide you with cheap hot water? -- Toytoy ( talk) 12:20, 20 April 2008 (UTC)
Solar cells are usually mounted above the roof rather that directly on the roof, becaus most roofs are not steep enough or ar not oriented due south. Therefore, almost all of the heat is moved away by convection on h efromt and back side of the panels. The actual roof is shaded by the panels, which decreases the heat input. Even if you do not have solar cells, you could make you r attic a lot cooler by mounting panels above the roof with lots of air flow below the panels. This is not common practice because ti's a lot cheaper to ventilate the attic.If your attic is hot in the summer, you should ventilate it regardless of whether or no you have solar cells on your roof. - 70.177.166.200 ( talk) 23:18, 20 April 2008 (UTC)
Extra heat is bad in the summer but good in the winter. A theoretically ideal rooftop installation will combine electricity generation with heat management, capturing the heat in the winter, and dissipating it in the summer or using the heat for low-power-density applications like heat-powered cooling. Residential solar is costliest power in terms of injuries per watt, because a single installation does not generate very many watts, while residential rooftop work results in a lot of injuries. Therefore, it better to implement a combined system with both solar calls and solar-thermal collectiohn, because the same number of tripr to the roof will result in more overall power. - 70.177.166.200 ( talk) 23:31, 20 April 2008 (UTC)
“ | Residential solar is costliest power in terms of injuries per watt, because a single installation does not generate very many watts, while residential rooftop work results in a lot of injuries citation needed. | ” |
When the wind blows, why do leaves travel in a circular motion?
24.197.166.190 ( talk) 16:14, 20 April 2008 (UTC)XYZ
What is the world's oldest tree? 99.226.39.245 ( talk) 17:34, 20 April 2008 (UTC)
Currently, the oldest (acknowledged) living organism known is a bristlecone pine tree nicknamed "Methuselah" (after Methuselah, the longest-lived person in the Bible), located in the Ancient Bristlecone Pine Forest in the White Mountains of eastern California, and measured by core samples to be 4,789 years old.
Swedish researchers found a spruce in Dalarna that has been dated to just under 10,000 years old
A cluster of Norway Spruce in Sweden includes roots that have been carbon dated to 9,550 years old, which would make them the oldest known trees in the world. Individual trunks only last up to about 600 years, but the roots from which they grow have survived throughout the entire period.
the Bristlecone Pine called Prometheus was a little older still, 4,844 years, when it was cut down in 1964.
Zrs 12 ( talk) 17:47, 20 April 2008 (UTC)
This article is confusing in that I'm not sure if it's one tree or just a few trees with the same genetic makup, the oldest of which has died. Perhaps it's the same as Pando, which would make pando the oldest tree. 99.226.39.245 ( talk) 17:56, 20 April 2008 (UTC)
What is the advantage of using radians as opposed to degrees? Zrs 12 ( talk) 19:09, 20 April 2008 (UTC)
Alright so here's another question:
This quote is from [3] "In other words, although M and B have never been in contact, B has been imprinted with M's polarization value, across the whole galaxy, instantaneously.
This does not mean that faster-than-light information transfer has occurred."
How are these two sentences not contradictory (The article says they're not but never explains)? Zrs 12 ( talk) 19:37, 20 April 2008 (UTC)
In the cAMP signal transduction system, a hormone detected outside a cell causes the activation of adenylyl cyclase within the cell, which produces cAMP, which in turn activates a protein kinase chain. It seems that this setup loses the information about what the initial hormone is - why don't all of the different hormones that work by the cAMP system cause exactly the same effects in every cell? -- Iaerhoiee ( talk) 19:54, 20 April 2008 (UTC)