dave
No. Scientists have needs too.
My grandfather described Duke Ellington as "jungle music". My father took me to see Ellington live in Bristol and I thoroughly enjoyed it (still do). Nevetheless, he had a similar opinion about the Rolling Stones. I can get my head around some modern Jazz, for example when Sting plays it, but I am trying very hard to recognise HipHop as music.
The scientific (?) expanation is simply that we are less adaptable as we grow older.
None of your d*mn business, troll.
A good question, but then what does "donna wynner" mean ? Does it mean you are the obnoxious real-estate agent or an obnoxious political commentator ? I am not sure which I find more unsavoury based on the evidence elsewhere on the net, and your posts in the forum.
dave
have you not been banned yet?
Not sure to whom that was directed, but anyway with more than 40 groans in just 10 posts I suspect that it is you that has difficulty making friends. But please keep trying if it makes you happy.
dave
Who, me? Far from it. With my stunning good looks, incredible sense of humor and ridiculous intelligence I seem to do alright. (to all the actual EFers out there I'm only kidding).
I'm not the one trolling around on websites to get human contact.
Anyhoo, back to the science. I need questions people, it's too cold to do anything outside today and I'm not feeling very productive work-wise.
OK Our Chemistry teacher once promised (when it was very popular as a commmercial product) to make us some Slime. Two years later we were still waiting, and she went and married another chemistry teacher and left the school to make babies.
So.... what is Slime made from ? I think the answer was given partly in the link, but I'd like to hear it (the answer) ooze from chemgoddess's mouth.
dave
Why don't ice cubes sink to the bottom of the glass ?
ice has a lower density then water and therefore floats.
But almost all substances contract to a lower density when solidifying. What makes water so different ?
This is due to the fact that when water is in its liquid form each water molecule can be closer to another than when it is in it's solid form. When in its solid form, the molecules have little motion and arrange themselves according to the dipoles of water and the appropriate distance to undergo favorable interactions. When most compounds (pretty much every thing other than water) go from the liquid to the solid phase the molecules get packed closer together than in the liquid form making it more dense, so the solid form would sink to the bottom of the liquid.
This is actually a very unique phenomenon specific to water and is basically one of the reasons we have been able to evolve life on this little planet we call home.
Most substances contract to a higher density, you have more molecules per unit volume. Solid water ends up having less molecules per unit volume.
when drinking coffee or tea or another hot beverage do water droplets when dropped from a tea spoon (gently of course) trace a path along the surface of the liquid in an outwards direction............... and why is this effect far more noticeable when drinking hot drinks with milk rather then without? also why do the droplets stay as droplets and not become immersed.
I have ideas for this, but would like to see what the rest of the world has to offer.
OK, everyone go make a cuppa!
1) Is it more important to wear sunblock on a 2-hour ski trip than on a 4-hour mountain trek?
2) Is it better to air the bedroom by opening the window early in the morning (when it's still dewy outside) than around midday (when the air is drier)?
Always wear sunblock when doing outdoor activities but particularly when in the snow as the suns rays are reflected off the snow and so you in essence get double the exposure.
As far as part two is concerned, I don't know. Personal preference, perhaps?
mmmmmm OK
1. not being experienced in the snow (only seen it once) but.... I would say the two hour ski (pending of course you are wearing the same clothes in both cases) reason being: reflectivity is far more efficient from white (even??) surfaces then say rocky ground. not sure if there are any particular considerations that should be given to UV absorbance by snow though.....
2. OK: depends what you call better? the end is the removal of unpleasant odours (volatiles) and particles i guess? if you have a full flow through the house, i wouldn't worry too much. but if you just opened the top of the window you might notice differences???
in the first case (high relative humidity, lower temp?) one could observe absorbtion of water by the particles and possible condensation of volatile species to larger particles. increasing particle size leads to a reduction in total concentration through coagulation of the particles. if there was a low flow this could lead to preservation of larger particles which could be then be smelled.
in the dry case, the removal factor is completely determined by the exchange rate of air through the room and natural effusion processes.
mind you i haven't taken temperature differences into account here..... bringing cold air into a warm room would change case 1. the opposite would affect case 2. (but only marginally i would guess)
Silly me. I meant 'more dense', like myself.
Is there any evidence that water was 'tweeked' to behave differently ? Otherwise we wouldn't have life.
As the wiki entry states it s made forn Guar gum, which a galactomannan. Galactomannan are a polysaccharides made of repeating units of mannose and lactose in different ratio (structure below).
When in contact with water, galactomanns form an highly viscous hydrocolloid. They also exhibit properties such as strength and break strengt (that is what was being sold as Slime, probably at a ludicrous price, considering that most of it is actually water)
Without trying to replace your long lost Chemistry teacher, she probably was planning to get some leguminosae seeds powdered (such as locust bean or carob, for example) and then add it to water.
anyone made that cuppa yet?
surfacace tension and different densities???? Just to say something.....