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Very interesting David, care to share some details?
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This has puzzeled me for ages, and no one seems to want to help me out.
Tell me, if heat makes things expand, shouldn't cold make things contract?
Why does ice make things expand then?
Which is it, heat contracts, cold expands, or cold contracts, and heat expands.
Blue
*BlueYer gettin deeper than Jack. . .ya'll got one of those streams (only when it rains maybe). . . does kinda make you wonder though. . . how yer personal parts shrivel up in the cold but the water expands and splits yer pipes when it freezes. . .b gosh darn science in every day life
*In general, heat causes solids, liquids, and gases to expand and cold cause them to contract. There are some exceptions over some temperature ranges. Such as water, which gets denser (contracts) when warmed from 0°C to 4°C. When warmed from 4°C upto boiling at 100°C, it expands like most materials. Ice is less dense than water because its crystaline structure holds the molecules farther apart than they are spaced in liquid water. That is an unusual property. Most all materials are denser as solids than as liquids.Some related tidbits: The old definition of a gram (mass of one cubic centimeter of water) was at 4°C, it's densest temperature.It's better to buy cold gasoline than hot gasoline because you pay by the gallon (volume) but will get more mass - 1.5% more at 45°F than at 70°F. When Hoover Dam was constructed they riveted the penstock by heated the undersized holes (holes expand with the metal) and cooling the rivets on ice to shrink them. Once inserted and the temperature equlibrated, they were never coming out.Hot water on the lid of a stuck jar works for three reasons: 1) the metal lid heats faster then the glass due to higher thermal conductivity, 2) metal has a higher coefficient of expansion than glass, and 3) honey/jam/etc get less viscous at higher temperatures.
*Its a good thing ice expands as it freezes, otherwise iceburgs would sink to the bottom of the ocean and practically never melt.
*Also - all the lakes in the North would freeze solid and never thaw!! Which means no fish either. Jack's stream may melt if it's small.-Rob
*Good observation Patrick!I live on a lake, but the only stream that I'm near is the openseptic field that I'm finishing today. Does that count?Blue
*That sounds like a good story, are you sticking with it?Blue
*Blue:I'm with David's thoughts. Water is one of only a few compounds that increase in size when going from a liquid state to a solid state. For most everything else you will run into, heat makes things expand and freezing them will make them smaller. Many things are assembled with the shrink-fit method of heating the hole and freezing the insert. Another example would be valve seats in heads and piston pins. This works especially good if the hole is aluminum and the insert is steel and you are removing the insert.Frank
*David, that sounds like a good story, are you sticking with it?Blue
*Life on Earth as we know it would be impossible if ice didn't float... Guess we got lucky.If you really want to kill time with science trivia (some is pretty neat), try New Scientist Q&A.For example, why is the sky blue? As you fly higher, it goes to black.
*The accumulation of ice at the bottom of the ocean would eventually raise sea level and we would all drown.
*No problem -- there wouldn't be a "we" to drown! If the whole ocean froze, it would rise by what? 2%? Now, with the ice -melting- the ocean should go up quite a bit and that beachfront property i bought in Arizona will finally pan out.
*Which story are you referring to? I told several. But I'm sticking with all of them. And here's another bit of trivia: zirconium tungstate shrinks equally in all directions when heated. By mixing it with conventional materials, a composite can be made to be thermally stable or to match the characteristics of other materials such as silicon
*Imagine the problems that would occur in construction if the coefficient of expansion for steel and concrete weren't as close as they are.Also cold is deceptive. cold is merely the lack of heat or energy so when you buy ice for the cooler your really paying for the lack of energy that particular water happens to have.
*Well at least I know who the brainiacs are! Thanks for ruining a good puzzle! Now what am I going to daydream about when I'm staring out the window of the house I'm working on?Blue
*BluePardon the i cross threadbut you could always daydream about all that prime topsoil waiting to spring forth and grow veggies after the apocolypse.i Keepin my topsoil where it belongs, under my veggies
*Too boring Patrick, but I do wonder why the experts tell us no to waste water!Let me see, I take a shower, using 5 gallons too much, and the water goes into my septic tank,and back into the aqufier. Why would they call that wasteful?Ahhhh, another mystery to ponder!Happy again,Blue
*Blue:I have some thoughts on your thought of water conservation. I grew up in a house with a shallow well and septic tank. I was trained to conserve water probably due to my mother running the well dry one day when I was a baby. This would be a spot shortage due to the time necessary to process the water through the septic tank and back into the aquifer. The well never went dry for the next 30+ years until Orkin poisoned the well.In systems that draw water from locations far from the point it reenters the aquifer, shortages can occour more often. In the counties around here, the municipal systems draw water from man made reservoirs fed by creeks. Only rain seems to fill these reservoirs, and this past summer was very low on rain so several reservoirs were on the verge of being empty and water rationing orders were given. Also the aquifer dropped and wells were going dry due to the lack of rain. I doubt much of the aquifer was drawn out and shipped to other locations in a manufacturing process, so most of the well water is put back into the soil near its point of exit. Deep wells for houses may pull from aquifers that are not fed from directly above. They may be fed from above miles away. So applying water at the point of exit may not replenish the aquifer.Getting too wordy, I'll stop rambling now.Frank
*Andrew,Why pay £7.99 for the book when you can get your answers here for free? The sky is blue because blue light is absorbed by the atmosphere and re-emitted in all directions. This scattering effect causes the whole sky to be blue while depleting the light coming straight from the sun of much of it's blue component. So the sun appears yellow (full spectrum less much of the blue). As the sun sets and the light travels through more atmosphere, more blue light is scattered and the sun and sunset appear more red. Why is the sea blue? It reflects the blue sky.
*Blue: Hopefully your septic does not recharge your well. It ought to placed downhill (where it will recharge your neighbors' well). But your point is well taken - for all those people with wells and septic, water conservation may save electricity to pump and fuel to heat, but it doesn't save water as it is returned to the groundwater.One of my pet peeves: How primitive standard septic systems are. Several days of residence time and it still comes out stinky into the leach field. With a aerobic (instead of anaerobic) system, I've made 10 gpm of toxic waste site water meet drinking water standards in a 1-hour-residence-time tank. A nice thing for the downgradient neighbors or stream. Biodegradingly, David
*Hi David,Your very close, but not quite right. Atmospheric molecules scatter photons, the do not absorb and re-emmit them. This Rayleigh scattering 'phase function' is not equal in all directions, the scattering of unpolarized light is stronger in the forward and back direction than in the side lobes. The sea is not blue because the sky is blue, although a blue sky will enhance the color of the sea. Seawater is blue because that is it's intrinsic wavelength of minimum absorption (with the exception of areas with phytoplankton blooms.) I've measured the spectral aborption of seawater and ice from Antarctic icebergs to explain the nature of a rare green iceberg I climbed and sampled, and published the results in the Journal of Geophysical Research (98,C4,pp6921-6928,1993), if you want the arcane details...As one gets into the details of some of these phenomena, many of the explanations are found not to be quite correct. Newton described the nature of the rainbow, but there is still argument over the cause of the supernumerary-primary rainbows, the streaks of color just below the rainbow. The closer you look, the less you know...
*Very interesting David, care to share some details?
*Sure, but I'll set up a new topic, "High Performance Septic Systems" and prattle on there. Aerobic digestors are a bit far afield from the original poster's question about ice expanding. -David