5 Strangest Materials 196
MattSparkes writes to tell us that NewScientist recently posted a quick look at five interesting materials with some very strange properties. There are liquids you can walk on, liquids that will escape containers by creeping up the sides, and magnetic liquids that can easily show you the shape of magnetic fields. The story also offers video links to display some of more amazing properties described.
Hammer, Feather, Freefall on the Moon: Revisited (Score:2, Interesting)
Hammer and feather are dropped simultaneously from equal heights (as measured by distance from the center of the moon), separated laterally by a distance substantially less than the moon's diameter. Both hammer and feather experience force from the moon's gravity proportional to their mass, and hence both accelerate at the same rate. Meanwhile, the moon is also accelerating towards the other two objects, but unevenly so: the hammer exerts a greater gravitational pull due to its greater mass. The moon is therefore subject to a torque, causing it to accelerate more rapidly towards the hammer.
The hammer is first to hit the ground.
Anyone who denies this truth is a spatially absolutist lunocentric whose refusal to recognize the validity of hammer/feather mechanics places him wholly beyond the help of Galilean metaphysics. Such hammer/feather rejectionists ought to be banished to the stars, for their own good and for the good of not only hammers and feathers but all subjugated smaller objects, everywhere, who find themselves victims of this scientifically perpetrated emassculation.
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So Did Jesus walk on water using cornstarch? (Score:2, Interesting)
Superfluid Helium video (Score:3, Interesting)
Re:Hammer, Feather, Freefall on the Moon: Revisite (Score:3, Interesting)
So straight up - does the hammer really hit the ground first? Replacing the hammer and feather with larger bodies - say, one (as the hammer's stand-in) which is the same mass as the moon, and the other (the feather's double) which is 1/10th the mass of the moon, it seems obvious that the more massive body will impact first, as it does have a significantly larger bearing on the moon.
Does the hammer's insignificant size relative to the moon negate any realistic gravitational influence it may have? Or for that matter, does the term 'significantly larger' really apply to the hammer and feather?
I think the 3-body dynamics may be so small at that scale as to be nearly nullified - I would suspect that the gravitational pull of the hammer on the moon would move it less than the diameter of an atom required to change the timing of the impact of the two objects. [Unless one is counting the impact of the electron shells prior to the impact of the nucleus, in which case I suspect the preponderance of heavier (atomic weight-wise) elements in the hammer, with correspondingly more electrons, necessitating population of the "larger" d- or f-shells, would be first. But again, it's not the gravitational influence of the mass of the hammer that would be the deciding factor...]
So.... anybody care to do the math?
Number 6 - Elastic fluids (Score:5, Interesting)
What makes this happen is the high molecular weight polyer. The molecules become entangled, and when poured, they pull each other along, resulting in the emptying of the container.
These fluids also exhibit other interesting behaviours, such as the Weissenberg effect, where when rotating rod is placed in the fluid, the fluid climbs up the rod. Also, add some particles (or bubbles), start stirring, then suddently remove the stirring rod, you will see the fluid snap back when it comes to rest.
One More I would inlcude: Plutonium (Score:3, Interesting)
Try this at home - if... (Score:5, Interesting)
And they mention conrflour - I'd stick with cornstarch. One time going France and Hungary to teach science, I figured I'd forego the big containers of white powder on the international flights... and getting to Nice, I found that you can only buy boxes of cornflour, not boxes of cornstarch in French grocery stores. You could get sugar-packet sized envelopes of it, which were labeled in French with something I could not read but I imagine said "You are in France. We are famous of our sauces. If you need cornstarch to make a sauce, then go away!."
Re:Water comes to mind (Score:4, Interesting)
It also has one of the highest specific heats of any material. (Highest of any common material.)
Re:Aerogel (Score:4, Interesting)
It's not quite that magical. A two inch layer of aerogel will keep things about as insulated as a really good vacuum thermos, however.
I know, I work with the stuff on a regular basis, we use it as insulation, by the 400 liter barrel. See some of my pics of some of the solid slabs I have in the office [flickr.com].
Re:More than five things... (Score:3, Interesting)
Re:I have one for you (Score:1, Interesting)
Me, I just make 10 bean and cheese burritos every week. Made with organic beans. onions, olive oil, cheese, green chile, habanero, sour cream, and tortillas. Cook once and freeze.
Then I cook other home made foods if I feel like it, or just eat a burrito if I'm feeling lazy.
1. Dilatants (Score:3, Interesting)
fluids that get more solid when stressed. The classic example is a mixture of cornflour and water - it's runny until you hit it when it becomes solid.
I remember playing with this mixture in grade school and since then I have always wondered why materials like this could not be used to make protective/bullet proof armor. Could someone explain this to me?
empty calories (Score:3, Interesting)