CaptainPanic

- 5000 meters is the distance you can casually walk in about 1 hour. - However, the world record holder took only 12 minutes, 37 seconds and 35 hundredth of a second. - And it's the distance an average nitrogen molecule at 25 degrees Celsius travels in 10.5 seconds (although usually not in a straight line). - It's also the same as 1562.5 average male African elephants standing on each other's shoulders. I'm not sure how much time the last one needs to climb all the way up.

Situation 1: The car is going at constant velocity and the flywheel is not moving. There is of course a normal engine that powers the car. Situation 2: The car approaches a traffic light, and needs to slow down. The kinetic energy of the car is transferred to the flywheel. The car slows down, but the flywheel gets all the kinetic energy and starts to spin faster and faster as the car slows down. Situation 3: The traffic light turns green. The flywheel will transfer all its kinetic energy back to the car. So, the acceleration of the car did not cost any energy. The flywheel can help the car be more efficient. You still need an additional source of power (an engine). How the energy is actually transferred is probably the same mechanism as any gearbox? I'd appreciate some comments on this part because I don't know for sure! But I can imagine that an engine can also go fast or slow, while the acceleration is being controlled with the gas pedal, clutch and gears. This flywheel just goes slower and slower as you accelerate, so you'd have to choose the gears differently, but I don't see why it would be really different.

If 71% if the Americans want to see an investigation, then why did they wait to express this desire until Bush was replaced by Obama? I mean, there IS a freedom of speech, so they would be allowed to express this desire also while Bush was still president, or am I mistaken? Or was Bush immune to any investigation as a president?

I think Europe, in general, is more free. But this is a change of the last years (US got worse, Europe got worse at a slower rate). This freedom does not have anything to do with the freedom to travel, but with the freedom to do and say whatever you want... Personally, I'm happy with my freedom in the Netherlands. I know however that it was even more free here about 20 years ago. The US has the largest percentage of prisoners in the world. That country, by the definition of "freedom", cannot be the most free. (Link 1, link 2 (wikipedia), link 3 (picture on wikipedia)).

I'm a bit skeptical about the fishing line idea, for a number of reasons. A 30 km long fishing line is hard to find. 30 km of 0.23 mm thick fishing line (rated 8 lb) will have a weight of 1.43 kg (about)... which is not negligible. The line does not have to be exactly vertical, so your sample will still land up to 30 kilometers away. Trees, houses and whatever will make sure that you cannot follow the line, and might even break the line. This simple method does not close the sample when it descends... something which is important for the test to succeed.

A flywheel is a large (heavy) wheel that is used to store energy. The energy is stored in the form of kinetic energy... the flywheel is spinning fast. When the energy is needed, it is transferred: the wheel slows down, and whatever application needs energy speeds up. Read more here (at exactly the place where you would expect the information to be ). A car could use a spring to store the energy too... but I'm not sure you would reach the end of the street... It's just not possible to put so much energy in a spring.

You will get more electricity from it. As an approximation, you can assume that it goes up linear with more sunlight.

Engine size is determined by power needs, not by the size in the shoe. Please check what kinds of engines are used in other applications that move people: scooters, toys (kids sometimes have little cars and motors) and segways. That should give you an idea what size you need. I am just guessing that it won't fit in the size you just described.... but I might be wrong. Electric drills might also work (as I said before) and vacuum cleaners surely have enough power to move you. I'm not sure what kinds of acceleration you can get. I'm sure however that you will either have to settle for a frequent recharging or large heavy battery. Why don't you design a battery-backpack? Some high voltage powerlines down your pants and you're done?

http://en.wikipedia.org/wiki/Monocoque If that is not for you (opening post), then it's for all those who open this thread and go "huh? what?".

1. Oxygen - keeps me alive and makes all our combustion processes work - pretty good for a waste product from agriculture. 2. Water - keeps me alive, but sometimes makes you wet, therefore no 1st place 3. Sugar - keeps me alive, and it's yummy, especially in combination with a mix of #2 and #4, also good for creating a bit of #2 and #10 upon combustion (digestion) 4. Caffeine - I love the smell of burnt coffee in the morning 5. Ethanol - keeps me alive in the weekends, also plays an important role in evolution and will be (one of the) fuels of the future 6. Steel - Hard, cold, useful, cheap, *bling* - engineers never have a wet dream, we have a hard, cold, shiny dream (I'll deny ever saying this). 7. Hydrogen - makes our sun, which makes life possible. Makes #2 when combined with #1 at elevated temperatures and/or pressures. Might therefore be a fuel of the future. 8. SiO2, glass - my favorite chemical to contain a bit of #2 and #5, quite inert, cheap, and also makes a fine wall that you can look through (also known as "window"). And almost the same thing, sand, is also pretty awesome if it's applied in large granular fields at the edge of the large basin of #2. In other words: I love the beach. 9. Plastics - even more than #8 not really 1 chemical, but more a group. Still, so useful, and one of the few products of oil that does not immediately turn into #2 and #10 when it's used. 10. CO2 - a gas that completes the carbon cycle, which we actively screw up now. Still, it's also a main component in burps and farts, and makes the beer foam. I cannot believe the crap all you put in your lists. If I ever encounter a planet full of deadly toxic materials, acids and explosives, I'll tell you. In the meantime, I will be looking for the stuff in my list. They make me happy. Sometimes I really believe that engineers and scientists differ more from each other than men and women. You're a crazy bunch *goes into hiding*

How do you collect bacteria anyway? a few aspects that are different are: -Bacteria will be much less common up there -You must avoid contamination at launch and when the sample comes back down! I'd say your biggest issue is to get your probe up there uncontaminated. I propose a weather balloon - those can go up to 30 km I believe? Make a timer to open the whatever-you-use-to-collect-bacteria Your second biggest issue is to find the probe back after it was up there for some time, again uncontaminated. How do you keep bacteria separated from the rest of the planet in the lab? You have ways to close off a system, right? Also, the winds in the stratosphere can be hundreds of kilometers per hour, so the sample will travel quite a bit. Again, I suggest that you copy whatever the meteorologists do... they probably somehow retrieve their equipment too.

There is definitely a future for Biotech in a huge country like India. A lot of pharmaceuticals are from biotech industry. A lot of food technology is related to biotech (I haven't seen the slumdog movie yet, but I assume that everybody eats in India, right?). Biotech includes all fermentation processes (think for example about beer). Biotechnology can often be studied in technical and non-technical universities. In the technical universities, it might be grouped together with chemical engineering. In the non-technical it can be more varied: related to food, or biology or medicine. And I'm sure that this summary is not complete. It's quite a huge field of science!

Read my post about scaling up your design. You had a working small scale design, didn't you?

Are you talking about neon lights by any chance? Although a neon light will not "change" color, it goes from no-color to luminous (giving off light), and all it takes is a few thousand volts... seems like that's what you asked for? Other gases can also do that. Also, check out sodium lights. Those work different again. I believe they also change color as a function of temperature (starting off red, then yellow?). Not sure.

Everybody who votes "yep" needs to grab a thermodynamics book, and study the 1st and 2nd law of thermodynamics. They make a lot of sense... and every time you turn on the engine, you "prove" them again.

So, although it's not literally in the question, I would have expected somebody to state the composition of the gas! Nobody bothered to check wikipedia for "farts"? In stead, everybody just started to share their own smelly experiences... lol. :D So what makes the stink? It has to be a whole range of (gaseous) chemicals in there, because all farts smell different. And what's the composition of the gas (because the stinky stuff is a very small part of it, but very "present")? I can produce at least two very distinctive ones: normal and beer-farts

Back-of-the-envelope calculation to check feasibility of the idea (assuming you can target with 100% accuracy). Let's say that there are 10000 tons of debris up there. Vaporizing the whole lot will take about: Cp aluminium = 880 J/kgK Melting enthalpy = 397000J/kg Enthalpy of vaporization = 10896000 J/kg (!) Boiling point aluminium = 2792 K Total energy to evaporate one kg of aluminium is: (2792-273)*880 + 397000 + 10896000 = 13509000 J/kg, or 13.5 MJ/kg total energy required for the whole lot is: 10,000,000 kg * 13,500,000 J/kg = 135 TJ (terajoule). With a space station like the ISS has 32 kW of power. Generating enough energy for the whole vaporization would take 133 yrs. So, yes, we need more power. Disclaimer: this was a short calculation, with numerous assumptions.

What is the actual question? We ask not because we're lazy to answer, but because asking the right question leads to the right answer. A molar volume has the units m3/mol. It is the volume of 6.022*10^23 molecules of a particular substance... [math]n_{1} = \frac{kW}{V_{1}^{*}(k\rho_{1}+\rho_{2})}[/math] -n is in [mol] -W is in [kg] -k is dimensionless -rho 1 and 2 are in [kg/m3] -V1* and V2* are in [?] Checking the formula so far, we can actually derive the units of the V1 and V2, using a dimension analysis. [math][mol] = \frac{[-][kg]}{V_{1}^{*}([-][kg/m3])}[/math] Formulas always have the same units before and after the = sign. The right side of the formula can only be in [mol] if you give the units [m3/mol] to the V1. Quite possibly, you use imperial/UK/US units. You can convert it all yourself.

Theo Maassen (Dutch). His show called "functioneel naakt" is awesome... for Dutch speaking people. Are ventriloquists stand-up comedians when they address the audience as well as... eehm... themselves? Jeff Dunham is pretty good (and English speaking).

To clean the debris in space, caused by satellite crashes and destruction of military satellites, we could build a space cleaner. Since it's already a vacuum up there, it could be called a vacuum cleaner, but I that might cause some confusion. I thought of on-purpose collisions with debris, deflecting debris into the atmosphere where it can burn up. Is there any armour (any material) that can withstand a collision at... say... 20000 km/hrs? It should be able to survive a head on collision with something orbiting in the other direction, and then be overdimensioned a bit. Let's ignore the fact that it should not be too heavy. Let's say we can put a tank into orbit... and put all its armour on one side. The idea is basically a big shield with engines... because a collision will also alter the trajectory of the "vacuum cleaner". Or is there any other way to do the job? A google/wiki search gave no results, possibly because I use the wrong keywords.

If you plan to use the tractor 10% of the time... and you have enough batteries to store ALL the electric power from the solar panels and windturbine: A normal tractor has a 15 to 480 kW engine. You have designed 7 kW of power (electric), to be used 1/10th of the time. Therefore 70 kW is available during tractor-operation. We can assume that an electric system of 70 kW will have the same results as a 140 kW diesel engine (because internal combustion engines aren't very effective, and produce a lot of heat - same reason why electric cars are more efficient). So, we can conclude that you are not thinking about the smallest of tractors, it also is no monster (probably not suited for mud or clay). If you plan to use it more than 1/10th of the time, you'll have a smaller engine. 20 liters of diesel But I want to show another type of comparison. You use 20 liters of diesel. That is the equivalent of 20 * 44*10^6 J (1 liter of diesel is 44 Megajoules). The total is 880 MJ. To generate that same energy with the wind turbine and solar cells (total 7 kW, or 7000 J/s), you need to run them for: 880*10^6 / 7000 = 125700 seconds, which is 35 hrs. Since the wind is not always blowing, and sun shines only half the time, we probably should double that... and half it because electric systems are more efficient. So: recharge time is 35 hrs. Of course, these are crude calculations. Did you check the weight of a battery bank? If you plan to replace them (manually?) you'd better check how many kilograms of batterypack need to be replaced.

Solar cell: http://en.wikipedia.org/wiki/Solar_cell Solar panel: a number of cells on a plate. Please be more specific, because there exist several types of solar cells... and the design includes several steps (which you can read about on wikipedia).

Guys, the OP does not seem to suggest memorizing formulas. I think for space flight, broadly speaking, you have different types of equations. I'll list some (not all): 1. Ballistics: Given the fact that your rocket produces F Newtons of force (thrust), where does it go? There is gravity from one, two or three bodies (earth, moon, sun) or even more. Calculations are in 3D (probably polar coordinates). 2. Engine calculations. Chemical reactions create pressure in the nozzle, which is (through nozzle design) turned into the maximum thrust. Different possible fuels can be used (liquid, solid and hybrid). 3. Possibly you can also study aerodynamics, which are especially important if you ever plan to return to earth. 4. Control systems. Measurements in the space craft lead to (computerized) decisions to correct something. This needs to be designed. Personally, I hate the math of the control systems. (For me it was mostly Laplace transforms, but I'm not sure how similar control systems in rockets and other chemical factories are). The links I provided are meant only to give more keywords. They contain little information... but if you manage to understand all of Wikipedia's links that you find on those pages, then you're going to be just fine Please note that you should not be afraid of the things you will encounter when studying this. People can dedicate years and years to every individual topic.

Apologies, I know that my post probably offends economists... I should not offend people. Perhaps we could create an "Economics" subforum in the "Pseudoscience and Speculations" forum? After all, speculation is what's happening on the stock market... and contrary to "real" science, economists usually warn that results from the past will not give any guarantees for the future. They also base their prognoses on feelings. Which definitely would put it in that Pseudoscience and Speculations forum. More apologies: I'm hijacking this thread now with this 2nd post completely off topic.

We should have started this thread with the definition of science. According to wikipedia: Science: Engineering: So, we can discuss whether engineering is a science or not... If you're doing a first time design, which requires experiments, then you are making an effort to discover with the goal to optimize and implement. That is engineering, but also science. Does that therefore mean that engineering is science? I believe that it is a bad idea to give people a chance to write a reply in a multiple choice question. You either click and vote, or you write and discuss... but the combination... this is the result.