bill@inteloc.UUCP (09/13/84)
> If you have a helium balloon in the car with you (and your fuzzy > dice), you will see something really strange: the balloon will lean in the > opposite direction the dice do. The explanation I've always heard for this > is that the balloon's motion is dominated by buoyant forces; when the air > in the car feels a centrifugal force and goes one way, the balloon goes > the other way. This is not strange at all: everything inside the car is being acted upon by the same resultant force. Since this force is toward the outside of the curve, the dice lean that way, while the baloon floats in the opposite direction. All the turning has done is to change the local definitions of "up" and "down" physically, while all of our visual clues support the "classical" (straight-line) definitions. -- T.F.Prune (Bill Wickart) {allegra | ihnp4 | tektronix} !ogcvax!inteloa -- "Operator, trace this call and tell me where I am"
rsmith.pa@XEROX.ARPA (09/18/84)
Another way to understand why the helium baloon wants to go opposite to fuzzy dice in a turning car: Imagine watching the car turn left from above. Imagine replacing the baloon for a moment with a blob of air of the same shape. What does that blob of air do? Nothing much - it swings to the left with the rest of the car. Obviously there are forces to the left that act on that blob-shaped region - forces arising from the surrounding air that caused the air to bend its path into a circular arc. Replace the air blob with the helium baloon: the same forces are acting on the blob shaped region. But the mass inside that region is less now! Thus the resulting acceleration will be smaller, and the velocity vector will be bent less. The baloon doesn't swing left quick enough to keep up with the car. Replacement with surrounding fluid blobs is a general way to think about all problems involving helium baloon-type situations.
rsmith.pa@XEROX.ARPA (09/18/84)
Wait a minute!! I meant to say in the halium baloon fuzzy dice comment: The mass is less so the acceleration is GREATER, so the velocity vector is bent MORE, and the baloon turns to left QUICKER than the surrounding air. My original remarks still apply for Helium 9875, a extreemly rare but very heavy isotope of this element. You have to drive the car pretty fast to avoid fallout problems.
chongo@nsc.UUCP (Landon C. Noll) (09/23/84)
> My original remarks still apply for Helium 9875, a extreemly rare but > very heavy isotope of this element. Helium 9875 eh?!? give us some facts on this isotope! :=) melting/boiling temp? sp. grav? whats the rest mass? is it stable? if not, give the decay system plus gamma levels if any whats the neutron cross section? what reactions does it have to say neutrons are protons additions? what about the electron shell shape? cost per gm.? i think ill add it my "Chart of the Nuclides", too bad it will be about 400 feet to the right of the chart. :-) chongo <still waiting for my He-5 baloon> /\55/\ -- "If they do distribute it, it is not part of UN*X (*)" J. Alton `84 (*)UN*X is a trade secret known by only a few people. ;-)
crandell@ut-sally.UUCP (Jim Crandell) (09/25/84)
> > My original remarks still apply for Helium 9875, a extreemly rare but > > very heavy isotope of this element. > > Helium 9875 eh?!? give us some facts on this isotope! :=) The answers to several of these are really fairly obvious. > melting/boiling temp? Melting point is about twice the temperature of the center of the sun. Several years will elapse before the boiling point is determined. > sp. grav? This one's problematic. After the nucleus absorbs the four innermost planets, its mass will not be accurately measurable by means of any existing technology. > whats the rest mass? Probably a Requiem. > is it stable? if not, give the decay system plus gamma levels if any I certainly hope so. If put out to pasture it could certainly be expected to eat up everything in sight. > whats the neutron cross section? The cross section of a neutron is about the same as that of a proton. (Did you capture that?) > what reactions does it have to say neutrons are protons additions? This is a very good question. A critter of this nature may well be expected to exhibit numerous reactionary tendancies. Protons may be additions, but the original building must therefore have been very small. (I'd estimate it would bring about 80 grand in the local market.) > what about the electron shell shape? Actually I'm not sure about this one. I'd suggest a chambered nautilus. A colleague of mine suggested Bourne. > cost per gm.? Please specify quantity. I'm fairly certain that single-gram pricing is irrelevant unless you have a source of fast neutrons handy. -- Jim Crandell, C. S. Dept., The University of Texas at Austin {ihnp4,seismo,ctvax}!ut-sally!crandell