do you know science?

Another one: Why do you travel faster on bicycle - or roller skates - than running?

I tested this on 5 people over the last week. And received the expected response: "Efificiency, wheels are more efficient than your legs." "Yes, but can you flesh out this efficiency thing? Why, how, wherefore?" Blank out.

Try it on your friends and health care practitioners. fun fun fun!

-- Rich

Missed original thread, but marble lands behind the mast (air resistance to wind of forward moving boat!)

For bicycle efficiency, your weight is supported by the seat, so all the energy of your legs goes into torque to create forward motion. Add toe clips, and you can add energy in return stroke. Gearing allows energy use to be coupled at the most comfortable/efficient rate...

Charlie

Vectors.

Ed

glass

It may be well known to you but nobody seems to have informed Alvan Clark, whose large refractors installed at the Lick and Yerkes observatories are working fine more than 100 years after their construction.

glass

Well, I could be wrong in estimation in viscosity, the flow can be really minimal. I remember some people in city observatory many years ago have spoken about that flowing, they were probably mistaken.

But there is no temperature point below which we can say the glass stopped flow now.

If even metal with melting phase change can flow ( known for aluminium wires under mounting pressure ) why not glass ?

glass

You might find to be of interest. If glass does flow the timescale is longer than the age of the universe.

As for aluminum wires "flowing", if you're referring to electrical wiring what happens is yield during repeated thermal cycling, not viscous flow. Nothing new about this--all metals have a yield strength, that doesn't mean that they flow when loaded to levels below that yield strength under everyday conditions.

Try to find a documented yield stress for glass. You won't find one--it deforms elastically right up to its UTS.

Further, if astronomical lenses and mirrors flow that would be detectable in days or weeks--they are figured to a fraction of the wavelength of light and any deformation would be detectable very quickly.

The notion that glass is not solid is pretty much an urban legend, although it has made its way into high school textbooks, thus becoming one more example of Paul Simon's "crap I learned in high school". Yes, it is structurally similar to a liquid, with no long term order--that does not mean that it does not have strong intermolecular bonds.

Well, there's "flow," and then there's "undergo plastic deformation."

On a geological timescale, even rocks "flow." (see "Himalayas.") ;-)

Cheers! Rich

Yeah, I remember reading such things, like "Glass - the rigid fluid", but it seems logical that 100-year-old panes of glass might be a little less precision than, for example, PPG Float Glass, but that could be attributable to the tools and fixtures that were available 100 years ago. ;-)

For example, I remember reading about how they made window glass that long ago - they'd blow essentially a big round bubble, poke it, and spin it, flattening it out by centrifugal force.

Cheers! Rich

That's BS. Besides, we have better outcomes than, for example, the UK, poor people included. How could that be if poor people were denied care?

I live amongst the poor people. The ones I encounter get the best of care.

Obama didn't reform anything, he's only made care more expensive and less available. IOW, it makes worse the very problems it was purported to solve. (I spent about six weeks studying the law.)

It's kind of a mix of perpetual motion and Keynesian economics, applied to health regulation.

-- Cheers, James Arthur

Then you must not be opening your eyes. I work as a volunteer spending over 300 hours a year, sometimes 500, helping particularly with the DD (developmentally delayed or disabled depending on how you want to phrase it) community. They are, in fact and almost by legal definition, poor people. They do not receive "the best of care." Not even close.

And two of my adult children happen to be disabled -- one suffers from grand mal seizures and is profoundly autistic (operates about like a 5 year old.) She has broken teeth against the bathtub, broken her arm, received 3rd degree burns on her inner thighs, just to name some of the horrors that take place with someone experiencing accidents during seizures. Getting her medical care, particularly dental care, in the US is a nightmare of historic proportions. You want an earful, just ask.

I've been told by one close US friend who is the owner of a large business and travels to Europe several times a year, that I should move out of the country for her sake. He has friends of his who did exactly that in order to secure better care for their own disabled children. Sometimes, I do wonder. Then I realize that I need to be part of solutions here. This keeps me always in mind of how to make improvements here and I'm currently working with several agencies locally to create some new services for the adult DD populations.

But the general circumstance is quite poor. Which is the point.

I know you aren't personally invested in what you say, not enough to actually spend any of your personal time disabusing yourself of your wrong impressions. But if you were serious, I can refer you to the department chair of the DECOD program at the University of Washington. Their teams have hooked up with Medical Teams International, some years back, to provide services four times a year in four locations in Washington. The interest in getting started happened when a Personal Assistant finally called from Walla Walla, unable to find anyone to help after making more than 100 phone calls in her area looking for dental services for one of her "not that difficult" clients. I have spent hours listening to story after story out of their experiences over the years. You might learn from it, if you cared or were serious.

To use your own vernacular, what you write is "BS." I live the life. You have no idea.

Tell you an interesting moment I recently experienced.

A 22-year enlisted vet who reached E8 pay grade as a First Sergeant in the Army came by as my insurance's 'adjuster' after a tree recently fell on my house. He did his job and gave me the paperwork and explained it pretty well and then we talked a little before he left. I'd never met him before and, as it turns out, my insurance company does not keep locals as adjusters -- they usually fly in from the central US as a rule. He was from a different state, as well.

I asked him about his service and being in Iraq in 1991 and he talked a lot about the experiences then, and in 2004 when he later returned to the area. One of the things he mentioned entirely on his own, as we hadn't even discussed it and I was focused on listening to him talk about his life, came up when I asked him one of my usual lines to find out the more remarkable experiences, "When you first went to Iraq, what hit you in the face about the people there as different from here?"

His response was surprising to me. Not the first thing he said, which was that the first thing he noticed is that there was no middle class, at all. But the second thing, which was that he's seeing here in the US, as he travels around the country doing his insurance adjusting work, a significant change in the middle class in the US. It's disappearing before his eyes, he said. And it worries him.

He recommended that I see the movie "Inside Job," which I haven't yet seen.

This was just two days ago.

Interesting. I will see the movie.

I have a great deal of respect for our First Sergeants.

Jon

The rope breaks.

The rock-rope system has both linear and angular momentum. Both will be conserved in the short term, air friction will reduce both.

Huh? You're a goddamned idiot!

Your stupidity is that you think they would come back at the twirler and wrap his neck or other stupid, incorrect physical application.

NO MATTER WHAT, it would twirl AWAY from the twirler without hitting him.

You should stand away from that lame moniker.

Goddamned cross posting retards.

We can start with you, and your abjectly ignorant Zimmerman Complex Disorder, which you just made a perfect display of.

One can "pull" a rope. Try "pushing" one.

That all depends on the rope's state of mind. If frozen...

If frozen, one is "pushing" a composite structure, not merely "a rope".

What is your first language, Nymbecile? It certainly isn't English.

Poor grammar is something up with which I shall not put...

Paul