Wikipedia:Reference desk/Archives/Science/2007 April 29

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

April 29

Hardened Boron Alloy Vs. Hardened Steel

If I have a padlock with a hardened boron alloy shackle(boron being a 9.3 on Moh's scale) would hardened steel bolt cutters be able to cut it?(hardened steel being in between 7 and 8 on Moh's scale)? Thanks, this has been driving me crazy —The preceding unsigned comment was added by 69.150.14.3 (talk) 06:53, 29 April 2007 (UTC).

I'd say it depends, bolt cutters rely more on leverage then hardness to cut something. If the bold is within the tolerance of the cutters I'd say there is a good chance that the cutters will cut it. Just because you are trying to cut something harder with something softer doesn't mean it will automatically fail. You can imagine cutting titanium foil with a pair of ordinary scissors, that's because of the design of the scissors, it is also easy to imagine an ordinary pair of scissors being destroyed by attempting to cut a titanium bolt. I think it would be a similar case with the bolt cutters. If you are actually trying to do this then one thing to remember is that the inside of the cutters, the point furthest in towards the hinge is where the most force is generated so if you were trying to cut something very hard try to stick it as far into the jaws as you can, but cut slowly and WATCH carefully, if the edges of the jaws start deforming a lot more then the bolt then you'll probably destroy the cutters if you squeeze harder. Vespine 03:04, 30 April 2007 (UTC)

Are we talking about cutting a piece of pure boron, or an alloy (boron melted into other stuff)? Hardness of 9.3 is for the element, not an alloy, and an alloy can have drastically different properties than any of its components in their pure states. DMacks 00:08, 1 May 2007 (UTC)

I would be very careful about "WATCHing" carefully. Hard materials tend to be brittle, and I can image either the bolt or the cutter exploding into some very sharp shards. So I wouldn't keep my face anywhere near the action. Bunthorne 03:27, 1 May 2007 (UTC)

beetle

I found an infestation of small; slightly larger than a ladybird, beetles covering tubs of rosemary and lavender...the beetles are very pretty; metallic green and bronze striped, head to toe. I had noticed the plants suffering but only recently seen the adult beetles... have a feeling i saw one pictured in RHS garden magazine a while ago, but cannot trace it.

Any idea what this is, and how to treat it? —The preceding unsigned comment was added by 84.70.57.152 (talk) 10:43, 29 April 2007 (UTC).

Could it be Chrysolina americana aka the Rosemary Beetle? (Wikipedia has an article on its family the leaf beetles or Chrysomelidae.) Here's a google image search. Is this your bug? ---Sluzzelin talk 13:17, 29 April 2007 (UTC)

My first thought was Japanese beetles. whatsthatbug.com is a good place for this kind of query. --TotoBaggins 13:23, 29 April 2007 (UTC)

Cancer in Argentina

Unpleasant subject but I need to ask. The average (According to Wiki) consumption of meat in Argentina in 100kgs per annum per person down from a high of 180kg in 19th Century.

Is this reflected in cancer statistics ?

Its a sensible question as we are told meat kills you etc. But does it.

If it doesnt I then have to look at other lifestyle choices in Argentina.

I do not know how to say thankyou beacuse of the structure of Wikipedia. So thanks now.

Paul

81.86.166.234 12:24, 29 April 2007 (UTC)Paul.mckenna at mac.com

I don't have the answer, but let me point out a few things to consider on the comparison:

1) Many other changes have also occurred since that time, so it would be difficult to determine which differences in health are due to which changes in diet and environment. There no easy way to compensate for this.

2) In the 19th century many more people likely died before they had the chance to develop cancer. For example, many women died in childbirth which would survive today and later develop cancer. So, you may actually find there was a lower rate of cancer long ago, along with many other diseases which tend to affect older people disproportionally. To compensate for this, you would need to look at the cancer rates for people of the same age. StuRat 17:04, 29 April 2007 (UTC)

Sound of P38 lightning

Hello

The P38 lightning was equipped with a forced induction apparatus known as a "turbosupercharger" It is because of the turbos the lightning lacks the raspy raw sound of its non turbo peers, notably the mustang, spitfire, and others. It has come to my attention however, that the wastegate on the lightning is fully open during takeoff. All of the gases are escaping unimpeded. I greatly enjoy the drone of the p38 engines and I attributed it to the fact that it was turbocharged, another aspect I enjoy. My question therefore is "why does the lightning still sound like a turbocharged engine at takeoff and is my logic behind liking the sound ill founded? —The preceding unsigned comment was added by 69.42.233.219 (talk) 18:59, 29 April 2007 (UTC).

Ah, flying machines! Do you have an audio recording? —Bromskloss 19:37, 29 April 2007 (UTC)

It is perhaps worth noting that the Lightning has two engines while the Mustang and Spitfire (and most other fighters) have only one each. I'd think that fact, and all the various sound interference and such that goes with two similar-but-not-identical noise sources, is a significant component of why you find the P-38's sound distinctive. — Lomn 15:19, 30 April 2007 (UTC)

Electromagnetic radiation as particle and wave

I'd like to understand the connection between the particle description and the wave description of electromagnetic radiation. For instance, how to describe a radio wave in terms of photons and how to describe a single photon as a wave? Thanks for opening my eyes. —Bromskloss 19:08, 29 April 2007 (UTC)

See wave-particle duality, wave function, photon, electromagnetic field, and electromagnetic radiation. If you want to go much deeper, look in to QED. Sorry for providing a bunch of links, but yours is a very broad question to which there isn't a short answer (or at least, not one that I'm capable of concocting). -- mattb 19:19, 29 April 2007 (UTC)

As far as I can see, the articles don't have an awful lot to say on what I am looking for. As an effort not to be too broad, let me give a specific example of what I would like to know: When analysing the properties of an antenna, we may calculate the electric and magnetic field it generates as functions of space and time. Could these fields be interpreted as photons? Could a static (electric or magnetic) field be? —Bromskloss 19:33, 29 April 2007 (UTC)

As the opening paragraph of the wave-particle duality article explains, (the) duality addresses the inadequacy of conventional concepts like "particle" and "wave" to fully describe the behaviour of quantum objects that on the quantum scale. quantum particles sometimes exhibit the properties of waves, sometimes of particles, sometimes the property seems to change depending on HOW you attempt to measure it. Trying to describe some of the behaviour as either particle or wave is what caused the duality in the first place. Vespine 02:45, 30 April 2007 (UTC)

Since you're not having much luck here, you might try posting your question at physicsforums.com. This kind of query is their bread and butter. --TotoBaggins 01:58, 30 April 2007 (UTC)

To clarify that: You cannot describe any situation with particles and you cannot describe any situation with waves. It is always wrong in both models. Just sometimes more wrong in one than in the other. —The preceding unsigned comment was added by 84.187.41.149 (talk) 04:00, 30 April 2007 (UTC).

Ah, that's a good point you (and Vespine above) make. Still, given an (inadequate) wave description, what would the (also inadequate) particle description be? —Bromskloss 07:55, 30 April 2007 (UTC)

Well... The de Broglie hypothesis is one useful relationship... -- mattb 13:49, 30 April 2007 (UTC)

But it doesn't tell you everything – there could be many different waves with that specific wavelength. —Bromskloss 15:10, 30 April 2007 (UTC)

Thanks for the suggestion. —Bromskloss 07:55, 30 April 2007 (UTC)

You might also find these equations helpful - Jefimenko's equations, which are the classical treatment, and the Liénard-Wiechert Potentials. Both of these deal with the ways that single particles interact with electromagnetic fields. In the most complicated analysis, you can use quantum mechanical effects; but you can decide what level of detail is necessary for your particular application. Nimur 20:25, 30 April 2007 (UTC)

fabic

At what temperture does rayon melt , does it have a lower melting point than ployester?

I don't have an actual answer for you, but you might find some useful information on google or elsewhere if you fix some of your spelling thusly: fabric, rayon, polyester. Confusing Manifestation 23:08, 29 April 2007 (UTC)

according to [1], "Rayon does not melt but burns at high temperatures" - Nunh-huh 05:52, 30 April 2007 (UTC)

Yeah, that sounds right. Rayon is made from wood fibre, it isn't a synthetic. Or, more accurately, it's not a petrochemical synthetic. Anchoress 05:58, 30 April 2007 (UTC)

Eye Colour and Genealogy

I am a white Briton and have green eyes. Does this mean I can say that I am descended from Celtic or Slavic stock with any degree of certainty? FreeMorpheme 23:02, 29 April 2007 (UTC)

Why would you think you're Slavic ? StuRat 03:46, 30 April 2007 (UTC)

In short, no. While "Green eyes are most often found in people of Celtic, Germanic and Slavic descent" they are also found "to a lesser extent in southern Europe (Portugal, Greece, Italy, Spain)." [2] There are three known loci and multiple alleles that account for eye colour. Even if you knew your genotype at these loci, is is unlikely to be sufficient for any type of definitive genealogical analysis. Rockpocket 05:31, 30 April 2007 (UTC)

Cyclone Technology

I was looking at the Cyclonic_separation article but it does not tell me when the technology was invented and who invented it. 202.168.50.40 23:08, 29 April 2007 (UTC)