Wikipedia:Reference desk/Archives/Science/2016 February 19

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February 19

Vehicle making software sought; open and or non-open source

What are all the software tool(s) required to make any type of a vehicle? Apostle (talk) 19:55, 19 February 2016 (UTC)

You'll need some type of CAD system, like CATIA, CADAM, or Unigraphics. And, of course, you will need the same software any other business would need, such as a database management system, an inventory control system, accounting software, etc. StuRat (talk) 20:07, 19 February 2016 (UTC)

I have AutoDesk AutoCAD. A Wikipedian advised to look at AutoDesk CFD (which I noted). Anything else you guys can recommend? -- Apostle (talk) 20:35, 19 February 2016 (UTC)

You really have to narrow down the type of vehicle. A bicycle can have a simple design, and use only basic software. Cars tend to have complex curves all over the place, so need an advanced surfacing software. StuRat (talk) 21:13, 19 February 2016 (UTC)

Those are the tools to DESIGN a car (CAD tools) - if you want to make one (manufacture it) then Computer-aided manufacturing (CAM) software comes into play - also inventory systems, office management, payroll - you name it! Even at the design stage, you'll probably want a slew of other software tools such as heat flow modeling, graphics rendering, crash simulation, parts costing, rapid prototyping, paint color formulation...again, too many to contemplate! SteveBaker (talk) 21:45, 19 February 2016 (UTC)

The list of simulation tools alone is too long to write. Just in my department we use ADAMS, VSIGN, CarSim, CATIA, Excel, Matlab, Mathcad, Hypergraph and so on, plus a whole lot of software we write in Matlab or Python or Excel. AutoCAD is not used by many OEMs for designing cars, it is sometimes used by suppliers, and for designing sheds and things. Also all OEMs I've worked for developed their own tools in addition to publicly available ones. The only open source packages I've seen used are Python, R and OpenFOAM, there may be others. Greglocock (talk) 23:43, 19 February 2016 (UTC)

(1) A software that deals with a 3D printer (plastic and metal)

(2) A software that can make a hand drawing into a 3D/4D model easily. - need to have the capability to transfer the file/diagram to (1)

(2) a) aero/air flow (car, plane, space), water flow (above and under), testing required from all angle.

Apostle (talk) 20:27, 20 February 2016 (UTC)

OpenFOAM will do the last task, I'm not a 3d modeller so I don't know about the other two. Greglocock (talk) 07:36, 22 February 2016 (UTC)

Greglocock: Thanks. -- Apostle (talk) 18:22, 23 February 2016 (UTC)

Cheap osmium

Per Osmium#Price and as confirmed by relevant sources, in 2012 one troy ounce of osmium costed about $400 which (if I'm not mistaken) is much lower than gold or platinum and is affordably cheap. Why is that, considering that osmium is the rarest stable metal on Earth (rarer than gold)? Brandmeister^talk 20:22, 19 February 2016 (UTC)

May be because nobody wants to buy it? Ruslik_Zero 20:51, 19 February 2016 (UTC)

Agreed. Compare it with gold, which seems far more useful for it's nonreactivity, such as for tooth fillings and electrodes. Gold also has a unique color, making it more prized for jewelry, etc. StuRat (talk) 21:21, 19 February 2016 (UTC)

Not to mention that osmium stinks (hence the name)... 2601:646:8E01:9089:516D:646:9764:EDC1 (talk) 08:07, 22 February 2016 (UTC)

Basic economics - the law of Supply and demand. If the supply is small but the demand is also small - then prices aren't necessarily that high. If supply is small but demand is high (gold maybe) then the prices are higher - if the supply is large and the demand is large (water maybe) then prices are low. SteveBaker (talk) 21:40, 19 February 2016 (UTC)

And in the case of seawater, the supply is high and demand is low, so it's just about worthless (although if you can deliver it to the middle of a desert, there any water is in demand). StuRat (talk) 22:39, 19 February 2016 (UTC)

In the middle of a desert even the seawater won't be appreciated. You have to desalinate it first. --AboutFace 22 (talk) 17:37, 21 February 2016 (UTC)

The sunlight can be put to work to set up a solar still to desalinate it. Or it can be used, as is, for evaporative cooling or to grow salt tolerant crops, like seaweed. A saltwater fountain in your house would also act as a humidifier. StuRat (talk) 23:44, 22 February 2016 (UTC)

Current (19 February, 2016) prices:

 Platinum   Pt  troy ounce  $944.00
 Palladium  Pd  troy ounce  $512.00
 Rhodium    Rh  troy ounce  $665.00
 Iridium    Ir  troy ounce  $525.00
 Osmium     Os  troy ounce  $400.00
 Gold       Au  troy ounce  $1230.74
 Silver     Ag  troy ounce  $15.38

Source: http://apps.catalysts.basf.com/apps/eibprices/mp/

If you are considering acquiring some, get Iridium, not Osmium. They are so close in density that it takes a precise scale to tell them apart, but Iridium is safe to be around and Osmium is nasty stuff. Plus, Iridium is rarer.

--Guy Macon (talk) 23:10, 19 February 2016 (UTC)

What percent of a normal battleship is hollow?

Or in other words, how much empty space is there? — Preceding unsigned comment added by Cheesewu (talk • contribs) 20:40, 19 February 2016 (UTC)

It's hard to tell exactly. We can take a VERY rough esitmate...The USS Missouri weighs 41,000 metric tonnes - and, of course, when it sits in the water, it pushes 41,000 tonnes of water out of the way. We know its' Length (270.4 m), Beam (33.0 m) and the depth of the water that it displaces (Draft 8.8 m) - we can estimate that the cross-sectional area of the hull close to the waterline is probably around meters of water pushed out of the way - so we can guess that the volume of the below-water part of the hull is around 4,600 square meters. From the photo of her in dry dock, it looks like the hull is about as tall above the water as below...but it gets wider at the deck and narrower at the keel...I'd guess the volume of the hull to be 100,000 cubic meters. There is some superstructure too - but it doesn't look like it's a big percentage. So if the majority of the stuff making up the structure is steel (density 7.8 tonnes per cubic meter) then there are about 5,300 cubic meters of steel in the ship.

Sooo...I'd guess a very, very rough number of 5% of solid volume...which fits reasonably well with a 'gut feel' answer. But if the real answer was twice or half of that - I wouldn't be surprised! So I'd say that between 90% and 98% of the ship was air. SteveBaker (talk) 21:36, 19 February 2016 (UTC)

Steve, you seem to have forgotten to include a number in "the waterline is probably around meters of water ". StuRat (talk) 22:37, 19 February 2016 (UTC)

I wouldn't expect a battleship to be substantially different from other modern steel ships, so perhaps we can just find a general answer to that. StuRat (talk) 22:37, 19 February 2016 (UTC)

To add to SteveBaker's answer. Simply put, if X fraction of the ship's volume is underwater, then the average density of ship is X times the water density, for 0 < X < 1. The density of water is about 1 g/cm3, steel density is about 8 g/cm3, and air density is negligible here, so in units of water density steel is 8 and air is 0. Denoting the fraction of the ship volume that is taken by steel as F (so that air is 1-F) the average density of the ship is X = 8 * F of water density. For X = 0.25, we therefore get F = 1/32 = 0.031 = 3.1%, that is, if ship is 25% underwater then about 3 per cent of ship is steel, and the rest is air. For X = 0.5, F = 1/16 = 6.25%. For X = 0.75, F = 3/32 = 9.4% - almost 10% of ship volume is steel. Dr Dima (talk) 23:11, 19 February 2016 (UTC)

Much simpler is, all ships are hollow all through. They are divided up into rooms inside with steel walls. Warships have smaller rooms so if a wall is broken and the room fills with water, the ship won't go down so far. Warships also have thicker walls so they won't break so easy. Battleships have very thick outer walls so weapons can't break them, though this doesn't work against modern weapons, so battleships aren't made anymore. Jim.henderson (talk) 02:21, 20 February 2016 (UTC)

Hopefully the OP was not confusing a battleship (a specific term) with a warship (a general term). Alansplodge (talk) 02:50, 20 February 2016 (UTC)

Yes, there is no such thing as a "normal" battleship as nobody makes them any more, and even when they did, each one was pretty much unique. SpinningSpark 16:05, 20 February 2016 (UTC)

Just because they don't build them anymore doesn't mean that there are none of them left out there - and even if they don't make them, why can't you discuss what a "normal" one was while they were still being built? There are plenty of battleships still afloat - no problem whatever with picking a typical example - and no problem (in principle) with answering the question. The only problem here is the practical one of somehow measuring the volume of a typical example of one of these gigantic beasts. I suspect, however, that our best efforts here that suggest somewhere between 92% and 98% air is going to be adequate precision for our OP...and there isn't much difficulty in establishing those as approximate limits on the possible percentage. SteveBaker (talk) 03:55, 23 February 2016 (UTC)

Wouldn't there be some simple way to calculate it, based on the Archimedes principle or something like that? ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:35, 20 February 2016 (UTC)

No, because ships have a complicated geometry that makes calculating their volume non-trivial, and they are not made of one single homogeneous material. SpinningSpark 17:57, 20 February 2016 (UTC)

Did any battleships other that the West Eriwick class[1] have a lead keel? --Guy Macon (talk) 18:42, 20 February 2016 (UTC)

Um...I don't think that is a real ship. It's seems to be a creation from the virtual gaming world. As far as I know, lead keels are only used on small vessels and models. SpinningSpark 19:11, 20 February 2016 (UTC)

(Note to self: next time, smoke crack after editing Wikipedia...) --Guy Macon (talk) 20:07, 20 February 2016 (UTC)

The largest vessel with a lead keel was the J-class yacht Ranger, launched in 1937. Tevildo (talk) 20:29, 20 February 2016 (UTC)

I still have my dad's toy sailing yacht from the 1920s, complete with lead keel. It's funny how we don't give children lead to play with any more; it never did me any harm... :-) Alansplodge (talk) 17:21, 22 February 2016 (UTC)

Note to self: If you feel like eating the keel avoid the soft, dense part inside. Sagittarian Milky Way (talk) 17:43, 22 February 2016 (UTC)

Work

If I move an object by applying a force, and I am impeded, in part, by friction, does the energy generated as heat still constitute work? I'm writing some slides for A-level physics, so I need to get my definitions correct.--Leon (talk) 20:59, 19 February 2016 (UTC)

From Work_(physics)

“ In physics, a force is said to do work if, when acting on a body, there is a displacement of the point of application in the direction of the force. ”

So, no, not usually. Heat is in a sense the disordered motion of particles, and we usually count displacement toward work only if it is a relatively well-defined body and it moves in a relatively well-defined direction that is roughly the same as the force. Turning it around, if I push a rock, friction will increase some temperatures, but no matter how much I heat up a rock, it will not move in any one direction, and we can't use heat to do simple work unless we use relatively complicated machinery. SemanticMantis (talk) 21:08, 19 February 2016 (UTC)

(ec) The work you did is the force you applied multiplied by the distance you moved the object. Assuming you're on level ground, the energy you expended in doing that work is split between the heat produced from friction and the kinetic energy imparted to the moving object. If the object stopped moving when you stopped pushing it (as is commonly the case in "normal" situations) then 100% of the work you did finally ended up as heat. If you pushed the object uphill then there is some gravitatational potential energy too. But the work you did is only the force multiplied by the distance - where the energy from that work ended up is an entirely separate matter. SteveBaker (talk) 21:13, 19 February 2016 (UTC)

Probably worth mentioning that it's only the component of force in the direction of motion that counts for this purpose. (Or "opposite to the direction of motion", for negative work; the point is that the component of force perpendicular to the direction of motion doesn't count.) --Trovatore (talk) 21:21, 19 February 2016 (UTC)

The answer to the OP's question is Yes. AllBestFaith (talk) 23:25, 19 February 2016 (UTC)

Leon's lesson and slides should introduce and explain the Work energy theorem. It is the reason work is defined in the first place. Dolphin (t) 00:20, 20 February 2016 (UTC)

The answer to the OP's question is unambiguously "NO", given that the classic way that concepts like energy and work and heat are defined necessitates that heat and work are mutually exclusive components of energy. The definition of concepts like Enthalpy depends upon defining work and heat as isolatable and independent constructs. Just as heat only makes sense when discussing the random motion of molecules (the heat of a single, undifferentiated particle makes no sense in isolation!), likewise "work" makes no sense when discussing the random motions of constituent particles of an object. A simplified way to think of these things is that work is related to the collective, bulk motion of all the particles of an object in the same direction, whereas heat is the random, individual motions of those particles relative to each other. Or another way to think about it is that the average displacement of all particles of an object due to heat is always exactly 0, whereas work always has a non-zero net displacement of those particles. this is a pretty typical chemical thermodynamics discussion of the difference between heat and work as it relates to Enthalpy. But no, heat is never work, if only because tautologically speaking, heat and work are defined to be mutually exclusive concepts. --Jayron32 01:12, 20 February 2016 (UTC)

I think you and Semantic must be reading the question differently from me. OP says: [D]oes the energy generated as heat still constitute work?

I'm not sure exactly what that means, but it sounds to me something like, "when I applied 500 N of force to the object in the direction of motion and moved it 10 m, do those 5000 N-m still count as work, even though, in the end, all they did was heat up the object and surroundings a little bit?". And the answer to that question is, yes, the work you did on the object is still work that was done on the object, in spite of the fact that the energy wound up as heat in the end.

If I were going to ask that question, I wouldn't use the OP's words, but I don't see how you interpret them in any sensible way to get a question with the answer "no". --Trovatore (talk) 01:23, 20 February 2016 (UTC)

Well, I can't interpret more than what the OP said. The OP's question is, and I quote, "does the energy generated as heat still constitute work?" The answer is definitely no, for the simple tautological reason that heat and work are defined to be mutually exclusive. "and moved it 10 m" in your example makes it unambiguously work, and not heat. Work done on an object is defined by the distance the object has moved, and has nothing to do with the energy lost due to friction or any other concerns. --Jayron32 01:35, 20 February 2016 (UTC)

I don't follow you. I moved it 10 m, and did work, we agree on that. Because of friction, the object did not keep moving; rather, the energy that I had done as work on the object was dissipated as heat. So now it is heat. But it was definitely work done on the object. Are you saying that it used to be work but is now heat? I don't think there's a tense logic involved; work is something done over a process, not a characterization of a certain bucket of energy. Thus I don't think there's any conflict in saying that the process involved the expenditure of 1000 J of work, and that the corresponding 1000 J of energy is now heat. That seems to me as a "yes" answer to the question. (I don't know what it would even mean to say that the energy is "now work".) --Trovatore (talk) 03:20, 20 February 2016 (UTC)

Jayron is correct, the answer to the question as stated is no, and the work done by the person pushing an object, is as SteveBaker said, it is whatever energy you have put into your effort (the applied force times the distance applied for the simplest case), but the work done upon the object (which is what the OP asked about) itself depends on whether you are accelerating it or decelerating it and upon interaction(s) with any fields present, less the heat generated by the friction. To be clear, both heat and work are changes to any object's internal energy as described in our article on the first law of thermodynamic. If the object you are pushing is on level ground and it doesn't accelerate/decelerate because of the friction, go up or down a hill, or have other forces acting on it, it will normally heat up due the friction and its internal energy is increased but no work is done on it at all because its velocity didn't change per the work energy theorem mentioned above. If the object does accelerate or decelerate the work done on it increases or decreases accordingly and because of the friction: the work done upon the object will be less than the work done by the person doing the pushing. In addition, when the object's temperature increases work is done on its molecules. -Modocc (talk) 01:56, 20 February 2016 (UTC)

No on the last bit where you say "when the object's temperature increases, work is done on its molecules". It would be correct to say that "when the object's temperature increases, the average kinetic energy of molecules increases." Using the word "work" to describe the motion of individual molecules is problematic, for the same reason understanding concepts like "temperature" as it relates to individual molecules is. Individual molecules can be said to have energy, but thermodynamic concepts like "work" and "heat" and "temperature" don't make sense on the individual molecule level. Concepts we use to describe energy associated with large objects do not port to the individual molecule level, because such concepts are based on statistical mechanics (even ignoring quantum effects, which adds an ADDITIONAL layer of problems), i.e. the statistics of a single thing are meaningless; statistics only makes sense where the law of large numbers applies. Simply put: when considering the motion of an individual molecule, concepts like work and heat and temperature don't make sense. Agree with the rest of what you said. --Jayron32 02:14, 20 February 2016 (UTC)

I propose rewording what I wrote so its less objectionable: its correct to say that molecules' average KE increase, then each molecule's KE increased on average, then ...work is done on every molecule with increased KE., can you agree with that? --Modocc (talk) 02:27, 20 February 2016 (UTC)

We're going to have to agree to disagree, then, because we're obviously not using the same definition of work. Work as a concept only applies when dealing with statistically large enough samples of molecules, the same way heat only does. Once you get down to the individual molecule level, your definition would remove the mutual exclusivity between heat and work, and make like all of thermodynamics illogical and unworkable. Just no. --Jayron32 02:47, 20 February 2016 (UTC)

At the macro-level I think we would have a problem then. For one can think of the work being done, which is what I am talking about, as what happens when there exists a cold condensate and its zapped by radiation so it is heated to a gas, lets say in the vacuum of space so that the gas disperses, which is analogous to what happens during the break in a game of 8-ball. Taking each molecule in isolation one has to apply the first law of thermodynamics to each of them do we not? They will each have a change in KE and internal change in temperature (vibrations with their atoms). -Modocc (talk) 02:59, 20 February 2016 (UTC)

Yes, but per the equipartition principle, you cannot separate the translational and rotational and vibrational components of molecular motion (heat) and analyze them independently the same way you can isolate work from heat on the macro-level. At the macro level, work is work and heat is heat, and they can be studied in isolation and it makes sense. At the molecular level, the equipartition principle states that translational motion (the "moving in a straight line" part of molecular motion) cannot be isolated from the other components that make up an individual molecule's kinetic energy; changes to kinetic energy are divided equally between all degrees of freedom for a molecule; in other words the "analogues" you're trying to make here between work and heat for the molecular level don't work because the physics is different. The "so-called" internal change in temperature you're talking about (the vibrations with the atoms as you say) is not able to be individually analyzed the same way that heat can be, so the analogy breaks down. Translational motion of individual molecules is still not work in any reasonable defintion of it, because of the equipartition principle. --Jayron32 03:18, 20 February 2016 (UTC)

And a gas expanding into a vacuum does "pressure-volume work". So there's still work being done there. --Jayron32 03:22, 20 February 2016 (UTC)

Can we please only consider molecules in isolation for the description part of the first law of thermodynamics specifies changes of internal energy, in terms of work and heat. When a single molecule absorbs energy only a part of the absorbed energy increases its KE (work is done to the system, which is a molecule) but its internal energy increases too such that its invariant mass increases. Thus we have the concepts of system, internal energy and the work done to that system which is to increase its KE. So what do we call the change in rest mass since its the change in the molecule's initial internal energy minus the KE change or, granted that I'm correct, the work done on it that is given in the article? --Modocc (talk) 03:57, 20 February 2016 (UTC)

What are you defining as the internal energy of a single molecule? The only thing I can think of would be things like the bonding energy between the atoms and the energy stored in the attraction between the electrons and the nuclei of the atoms. Unless the molecule undergoes a chemical change of some sort, normal collisions below the threshold energy to cause bonds to break will not cause changes to the internal energy of the molecule. --Jayron32 04:14, 20 February 2016 (UTC)

One could ask the same question of a billiard of which there is no definite answer since its heat is stored in different ways depending on the material since each substance has a different specific heat. Its been years since I've read about lasers being used to cool particles, but I suspect lasers can be use to either heat (obviously) or cool a suspended buckyball and there will certainly be a lower limit to the energy which can be removed in this manner; conversely one can heat it until its bonds break and it vaporizes. If we should have a collection of a million of these we call it heat, but the same internal processes store it regardless of their number. Ah, I do see that we have an article on laser cooling, and from reading just the first couple of sentences I see that it should be of some help here (but I've not read it yet). Update: Shucks, I see that the technique started with low density atoms and is limited to simple diatomic molecules, so not terribly useful. To cool off, deep space is perhaps the better place to send the buckyball I would think, but a cold enough chamber in which it is magnetically levitated should do the trick too. --Modocc (talk) 04:33, 20 February 2016 (UTC)

The heat that the OP's work produces can drive a Heat engine which can do more mechanical work. By Carnot's rule the efficiency of the conversion from work to heat to work must be less than unity, but it can be repeated until the Heat death of the universe which is not expected soon. That will be when there are no more temperature differences or other processes that can be exploited to perform work. Please conserve our universe by minimising your entropy footprint. For your edification, this constitutes a work of Leonado da Vinci. AllBestFaith (talk) 14:50, 20 February 2016 (UTC)

• We might all do well to remember this question! Seemingly simple, yet such deep disagreement. Upon re-reading, I can see now how Trovatore and AllBestFaith can see an easy "yes" answer. Trovatore's simplified example stands as correct. However, it's not clear if that's what OP meant. I also naturally interpreted the words similar to Jayron, Steve, and Modocc and got the answer of "no", where we were more focused on the idea that heat is not work. So OP will do well to clarify the wording, both in terms of the questions here, and for the A-level students! SemanticMantis (talk) 15:44, 20 February 2016 (UTC)

I have enjoyed reading this discussion, even though I'm only slightly clearer than I was before. Perhaps I meant, "has work been done", rather than energy itself constituting work. I'm not sure what I can add to this, other than, thank you all.--Leon (talk) 19:21, 23 February 2016 (UTC)

After reading Trovator's posts which jogged a few dormant brain cells that I should have been using yesterday, I struck most of what I wrote because I somehow managed to mangle the OP's description of the work with the internal energy state changes (the heat generated) which the work–energy principle doesn't consider. "This section focuses on the work–energy principle as it applies to particle dynamics. In more general systems work can change the potential energy of a mechanical device, the heat energy in a thermal system, or the electrical energy in an electrical device. Work transfers energy from one place to another or one form to another." [2]. --Modocc (talk) 21:00, 20 February 2016 (UTC)

The Work (physics) article gives "skidding to a stop" as an example. In general, when you push a piston you might be doing a number of things - one being, you're doing work against gravity by pushing it up, creating potential energy; another being, you're doing work against friction by rubbing it up, creating heat energy. Either way, the work is done - whether you can spend it again is a different question. Wnt (talk) 18:42, 21 February 2016 (UTC)