Engineering

Solar Leaf Cheaper Fuel Cell I came across these two articles recently and it has left me with the impression that we might see some big strides in the solar energy front in the next decade. The first is a solar leaf that can provide hydrogen and oxygen from water economically, the second is a fuel cell manufactured from reasonable materials. What do you think? If a President set a goal similar to Kennedy's man on the moon, could we make serious strides toward energy independence in a decade?

just tinkering building a pellet gun we're using a recycled fire extinguisher aluminum canister we drilled and tapped a hole in the bottom and threaded a one way valve from a bicycle inner tube in the back (and glued it) so it's 1/16 wall thickness (maybe 3/32 but don't think so) and just wondering about safety it handles 100 psi well and shoots well with that pressure. Will the aluminum fatigue? Are we holding a shrapnel bomb at that pressure? I haven't the slightest clue about the formula for designing such a contraption we're just rednecks drinking beer and having fun on the weekend. Thanks in advance because it would not be pleasant to be missing my beer drinking…

If you were given the task of designing the simplest vehicle possible, what would the components be? Assume at least one or two passengers and possibly some cargo. Also assume you would want it to be able to cruise for extended periods at highway or slightly under highway speeds. By simplicity, I am mainly referring to the number of parts and their complexity. Air-cooled engines seem simpler to me than their water-cooled counterparts, for example. I don't know much about electric motors or other types of combustion engines, e.g. rotary engines. A related issue is how much fuel efficiency advances can be achieved alongside simplification of systems. The air-coo…

It is a popular idea that residential energy users can install solar panels and feed their unused energy back into the grid. But doesn't the voltage have to be at a certain level to effectively traverse the grid? Does the transformer that intermediates power between the lines and residences allow weak voltage charge to flow backward? I wouldn't think the current would be strong enough to add anything to the grid, but if it does, how does that work?

We could convert all autos to electric, and phase out all fossil fuel use, except for airplanes. As long as humans use airlines for transportation, they will need fuel from oil or something else. Jet fuel from corn?

It seems to me that a car should be water-tight, so you can survive a tsunami by getting inside your car. But I think cars are death traps in a tsunami. Anyone know how long it would take a car's cabin to fill with water if getting battered around by debris from a tsunami? I propose people living in vulnerable areas should have water-tight cars and it doesn't seem like such a difficult thing to water-proof a car's cabin.

Is it possible to design a machine that can replicate it's self if we give it the materials it needs? I'm thinking like robot that is programed to build replica of it's self. or even like printer that print it's self. Did any body accomplish any thing like this before? If not, do you think that it could possibly be done. If not, are there any law's of physics that prevent this. (do cells do this?) I couldn't find any good results on Google.

I want to start a debate on renewable energy versus nuclear energy. Topics to consider. politics, cost , safety, spent fuel , fuel reserves etc.

So, I'm not an engineer, but I think this is pretty sweet, and I figure engineers might enjoy it even more than I would.

As a kid I was electrocuted by being in contact with approximately 400 volts ( alternating ) at a street light . I don't know how long this was for as my perception of time became distorted . Possibly , it lasted less than 5 seconds . I don't recommend anybody intentionally makes contact with a voltage like this in this way . Funny as it might sound , does anybody have any idea of how much energy I dissipated ?

I've been working on a project for a number of years now. It's *almost* completed. In short, I believe it will be the world's most powerful gun powered by "hardware store-level technology". Not the largest, mind you, but the most powerful. Muzzle energy should be in excess of 2 MJ. In any event, it's a fun project that I figured folks around here might get a chuckle out of. Below is a pic. It's a bit dated; lots has happened since the pic was taken, but it should give you an idea....

Is it easy to make a safe one? I'm not concerned with mobility.

for small wind turbines (domestic uses), do they only influence the Cp with controlling the tip speed ratio. And do nothing to the pitch? was just wondering. I assume at small levels that it becomes too expensive to put in a controller to and movable blades to allow that. AND, if anyone knows of any internet resources where the techniques are discussed how the TSR is controlled let me know of them? I've seen things that are too basic or too complicated. nothing in between.

Can some one share some good test book or even video lecture on mechanical engineering

Well here we go. First off i am working on this concepts for a project of mine. and i am not educated in the usage of magnets. So i ask you. My project is basic I am curious what the power requirements would be to magnetically levitate a 4000 pound object that is roughly 20 ft X 6ft in size. The suspension will have 4 points 1 in each corner and must be levitated a minimum of 6 inches. if there are any options with actual magnets and opposing forces please leave some feedback because that would work too. if anyone could help with this would be great.

i have one question. How do I determine pipe schedule number for a given design pressure? Is there any simple formula for determining the schedule number? Please advise me. Thanks a lot.

Hi, I'd like to know if it is possible to build a home-made laser pointer, without opening up a CD-ROM/DVD burner to extract the diode needed? If it is possible then does anyone care to explain how this is done or provide a link/book/source on this? If not, what's the cheapest way of aquiring the materials and/or devices needed to build one. Its for a home-fun-project, so nothing too serious but it is worth noting that this will be my first. I'd just like to know more about how a laser works and have done some reading on the web, but I guess you just don't get it 'till you get your hands dirty.

Lets say if i have a test tube (diameter 3cm and height 30cm) seal with a rubber. in the test tube there 100ml of water = around 10 cm height. if air was flow into the test tube from bottom of the tube with flow rate around 20L/min, and after a few sec, the rubber was push out. in general i understand that the pressure inside the test tube is higher than atmospheric pressure. but i cant find any mathematical solution that relate flow rate and pressure to proof that the pressure inside the test tube is higher than outside. can anyone explain it to me.

Can we make a portable bridge? (Model) What is the material required? What are its advantages and disadvantages? Thanks in advance. |rkt|

Hi! I was just wondering, how exactly does a nuclear reactor work?

I wasn't sure as to where this post should of been posted in. But does anyone have any ideas how to build a mousetrap propelled airplane? Any imput will be appreciated.

I have been peeling pees for few days. I am really exhausted and wish to make a PEA-EXTRACTOR machine. Is anything like this has ever been created? If yes, kindly provide me with some details. If no, let us discuss how it can be made!

i want to understand ---- maximum output=14 PS/7500 rpm & maximum torque= 14 Nm / 6000 rpm (a bike engine's specs)--- thoroughly what it means and how it affects bike ride (performance,power,speed) Thnx for ur time

Let's say we have two rods/bones/whatever, that are the same length and mass. And let's say that one of the rods is solid and the other one is hollow. Can someone explain to me why it is that it's easier to twist (i.e. shear forces) the solid rod than it is the hollow one? That seems completely counter-intuitive. And also, just correct me if I am mistaken here; since the solid one is easier to twist, that would also mean that its angle of shear (i.e. θ) would be greater than the θ of the hollow rod, right? This concept is driving me mad, someone please help me.

a mechanism to store mechanical energy then release it, like wounding a giant spring then having a full seize car go 100 miles. the closest i found was NASA's human powered plane. did you hear of anything similar?