cjohnso0

I have never heard of a tensile test machine being used to check hardness. You would do well to send a sample to a metallurgical test facility for the test. Around here it would not be expensive (<$100 US) for a simple hardness check. I imagine any correlation between hardness and tensile strength would be very inaccurate.

Sounds cold in there I'm interested in the expense of the firewood over the 30 days, including any labor to chop / move the firewood (as time = money in my book). Also, what part of the world do you live in? Cold climate? Moderate? I'm not sure of the heating cost with wood where I live, but it would (wood?) make a difference. Oh and one more, what's your typical electric bill? Sorry for the inquisition, and I'm not trying to come off badly if it sounds it, I'm interested in the circumstances, as I head with oil and no wood, and it's pretty costly. Thanks

How else could he fluff up a one paragraph story to 10 pages of BS? I would leave that part out too YT, as it kind of admits that you were doing something wrong, unless you were, in which case we don't know the whole story.

Well, my ambitions have definately changed over the years: <=13 or so: Fighter Pilot, Cop 13-15: Computer Programmer or Engineer 15-17: Musician (got my first guitar) Computer Programmer or Engineer 18-26: Musician, Mechanical Engineer 26-the end: Provide for my family, Raise my boys to be good men, and maybe succeed in my career, oh and still become a musician, at least part time... Currently, i'm in my 29th year and I still suck at playing that first guitar, but I am living the (no so dreamy) life of a Mechanical Engineer, working in aerospace. My kids are so far so good, but their still too young to tell if they'll turn out like I hope.

29 (really, not 30 until august), Male, from the USofA

I had a similar problem way back in Middle School. I got my face slammed into a locker by a guy who stole my football at recess. We both ended up suspended (internal too, yech). Mind you, I never hit, threatened, or provoked this guy either. So it's definately not an isolated case. As for the OP: I agree with insane_alien, you should write about the circumstances, they probably don't really care what you write, just that you put in the effort. Just make sure you emphasize that you were the victim, and maybe throw in some self defense stuff. If you felt like you were in physical danger from the bullies, you are more likely justified to strike back. I can't imagine writing a 10 page essay for a crime I didn't commit... Good luck to you!

From my understanding, the engine in the OP is an open rotor design, off of an Antonov. Open rotor is not another name for turboprop. Turboprops have the propellor connected to the turbine engine via a gearbox, while the open rotor design has a direct connection. Kind of like removing the cowling from a more traditional jet engine and extending the fan blades. Turboprops are efficient to about 450 mph, after that speed props are not as efficient. Open rotor designs are trying to solve this problem with the counter rotating blades and new swept blade designs. disclaimer: some of this came from wikipedia, but it can't be too far off. They have good articles on all jet engine derivative there. Also check out the new Airbus A400M, real nice military transport to replace the C130's and such. It's a turboprop design.

I'd say that you need a tiny bit of algebra, although the amount I'm talking about is pretty much common sense. X+3=7, find X kinda stuff. More than that and I doubt you'd really ever use it. I've been through tons of algebra and calculus classes in my many years of school, adding up to a Masters Degree in Mechanical Engineering. I know practice engineering in the aerospace field, and I never use calculus, and very rarely use algebra. Many of the engineers I work with dont' know calculus (never did) and don't remember algebra. But... I would hate to be in my position without the know-how.

Hi scillearner, I don't understand why you state that the fundamental frequency of a guitar string is at the center of the guitar? The open string (unfretted) produces the fundamental frequency when it is excited (plucked). The fundamental mode of a vibrating is such that the wavelength of the vibration is two times the length of the string. Which is why the string vibrates elliptacally, or only looks like half of a sin wave. When you lightly touch the string at the 12th fret (1/2 way down the length), you are adding a node to the vibration. This added node has the effect of reducing the wavelength by half, thus doubling the frequency. As DrP stated, the strings are tuned to different frequencies based on a combination of mass (material and diameter) and their tension. The frequency produced by a vibrating string is related to mass, length, and tension. You can find the actual equation all over the 'net. Hopefully I'm not too far off, it's been a long time since vibrations in college, but I do get lots of guitar playing in these days.

Hey everybody! Hopefully someone has tried this without a computer sometime in the last 20 years or so. I want to draw a graph of cartesian equations, without using software. How does one go about doing this? Example: [math]x^4=x^2y-y^3[/math] I know what it should look like, as I can cheat and graph it online, but assuming my computer explodes tonight, how can I visualize something like this? Do I just plug in x = 0 and solve for y, etc...? Or is there some kind of easier path I should follow? Thanks in advance! Chris

Easy to Hard: Physics, Chemistry, Biology. Although my grade was the lowest in Chem, but that was due to girls, not the coursework. In college chem was a breeze. As posted above, physics is derived from math, since I like mathematics, that makes is easy. Chemistry isn't really too bad, it's mostly balancing those equations and memorizing the table of elements. Biology on the other hand... Not my cuppa tea

I wear analog watches only. I like the ones without numbers, and I seem to be able to read them at the same speed as digital, at least not significantly slower to really notice. I think I like them for 2 reasons. One, they look cooler. Two, I'm drawn to mechanical things much more then digital ones, likely due to the engineer in me.

Mine's quite original, good old first initial, and most of my last name. Since there are so many Johnson's out there, the system at college cut my last n and stuck a zero in there. Guess I was a little too late. And since I can't stand having multiple name, most everything is now cjohnso0.

I didn't believe it at first, but Atheist is correct. I even double checked it with Excel. If you multiply everything out, you see that zero is the only answer. Set up an equation like this: [math] c(v1 + v2 + v3) + d(w1 + w2 + w3) = 0 [/math] Sub in the values for the v and w components and you'll see what Atheist is talking about.

Excellent reply waitforyoufo. I managed to graduate with a degree (or two) in Mechanical Engineering while working full time at night to pay for it. Mind you, my job wasn't super hard and I could do homework when I wasn't busy. How hard it is is entirely dependent on you. Same goes for your career following your education. Some people would put in 10 hours on a paper / project / homework and get a C, while others put in 1 hour and ace it. The workload will not be light, you take about 6 classes a week, not including labs. And they all have homework and projects to do. When you're going after an Engineering degree, you need to realize that this is the reason you are at school. You are not at college to goof off and party (at least not all of the time). We lost about 90% of the incoming ME's over the course of four years. Most went to other majors, everything from EE (electrical engineering) to CJ (criminal justice). I think some wanted to party more, some found it too much work, and some just were way out of their league. Bottom line: If you love engineering you'll do fine. I think you really need to enjoy math and problem solving. You sound pretty good at problem solving. Math in college is taught differently that in HS. I found it easy, while highschool wasn't a cake walk. Most engieering math is based on calculus and it's derivatives (ha ha ha). You'll probably have an economics course, but that's the name of the course, so you expect it. And as mentioned by waitforyoufo, the other courses are really really easy A's after an Engineering course or two. Just stick to it, don't party too too much, and you'll do fine.

Given the extent that computers are utilized in the auto industry. I don't think you can go wrong with it. If you end up as a design engineer, you won't do much programming. A lot depends on what you want to do with your education and where your interests lie. I'm not in automotive engineering, but aerospace. My job does not require that I know diddly about programming. However, since i've been programming since the Commodore was out, I have a pretty good grasp on it with no real formal education. I use it pretty regularly to make our jobs easier, scripts, databases, office automation. I gives me an edge in the machine shop too. I can figure out how those crazy machines are programmed much easier than someone with no computer background. BTW, at my college, they wouldn't let me double major in Engineering and CS, I tried! So I stuck with Engineering only. If you like CS and Engineering, go for them both.

Does this need to be man/woman powered? Or would say a gas powered generator work? Solar Cells - I always think of Africa as sunny and hot (unless in the rainforest I suppose...)

DominionX10, FWIW, i'm an mechanical engineer who works on turbine engines, and I work regularly with high-temperature super-alloys. Does this metal need to be cherry red or do you have a certain temperature in mind? As far as I know, all alloys lose strength as temperature increases. You need to define what kind of strength you need and the operating temperature. But read on for some alloys I deal with regularly. Also, when metals get cherry red, they get very soft and easily deformable. One of the strongest materials used in turbine engines at standard operating temperatures is Waspaloy. This is a nickel-based alloy. At ~1200F the tensile strength drops like a rock. The most common high-temp alloy in turbine engines is Inconel 718. At ~1000F the strength drops like a rock for this alloy as well. Cobalt-based alloys are also used at high temperatures, but again, their strength is greatly diminished at high temp, for example, L-602 has a yeild strength of 180,000 psi at room temperature, at 1000F this is reduced to 120,000 psi, and at 2000F you are down to 10,000 psi. Titanium is not a high temperature alloy. While used extensively in the engines, it is used forward of the combustion chamber, where temperatures are low.

Well, on first try I came up with an maximum inner sphere size of ~180.2517mm. Basic methodology was as follows, refer to this page (Figures 2 and 2A) http://www.kjmaclean.com/Geometry/dodecahedron.html I took the 100mm sphere diameter and set this equal to the length of one of the dodecahedron sides. Using this, you can find the length of the sides of the cube which fits perfectly into the dodecahedron. I came up with cube side length of 50/cos 72. Next, I figured that the tetrahedron inside the cube would have the closest packed 4 spheres. So I found the length of it's sides, which came out to be 50*sqrt(2)/cos72. Using this, the radius of a sphere circumscribing the tetrahedron is r=sqrt(6)/4 * SideLength. Subtract 2 times the radius of the balls, or 100mm and I got my answer. Final equation was (hopefully) D = 2*(50*2*sqrt(3))/(4*cos 72) - 100 which was ~180.2517 Let me know if my method is way to confusing to read. Not that I'm 100% sure i'm even close....

After looking at the wikipedia article, it looks like they stabilize by varying the speed of the individual rotors. The benefit over a helicopter is that you don't need to vary the pitch or the collective. To use just one engine, I would assume you would need 4 infinitely variable speed transmissions, one per rotor, to enable vehicle control. How large of a vehicle are you thinking of here? The one referenced in the article is C130 sized...

Well, I think this works, double check em if ya like. [hide] A=8 D=5 E=9 M=1 N=7 O=0 V=3 ADAM=8581 AND=875 EVE=939 MOVED=10395 Got it by the given GOD and fiddling with the #'s [/hide]

So I've been recently reading This is Your Brain on Music. Just a few minutes ago I've had an ear-ringing experience (not the first, probably not the last) I work in an office connected to a machine shop. So ambient noise is that of machinery, a/c, people chatting, computers... you get the idea. Anyhow, I'm sitting here typing away and I get the ringing. In my right ear the ambient noise drops to about 1/2 it's current level and a tone of around 1kHz takes over. This is in the right ear only, and it feels a like there is a little more pressure in there. This goes on for about 15 seconds, then the pressure returns to normal, the frequency increases until I can't hear it, and the ambient sound level returns. What the heck happened? This has happened all of my life, the but the above mentioned book has me thinking about it. Did my brain fritz out? Did the eardrum go nuts? Or was it aliens trying to communicate? Internet search showed tinnitus (sp?), but that seems to be caused by trauma, and to be fairly persistant. This is like a once every 6 month occurance kind of thing. Any ideas? thoughts?

A few years ago there was a show on The Discovery Channel that had a computer mouse pointer which was controlled by a human brain. I believe the gentleman controlling it had lost his arms, or at least the use of them. They plugged into the nerves that control arm / hand motion. It was very cool, I'll try to find a link somewhere, nothing on the first page of search results.

I'm not sure what the point of this poll is? You need to build and test two similar systems, one with MagGears, one with standard gears. At the least you need to have some theoretical efficiency data. I did see some calc's of inertia and energy but nothing on what you are really trying to prove. I'm not trying to be negative on this but you can't base the validity of a product based on a few guesses with no data to back it up. Also, I'm curious as to whether or not the MagGears can turn a 4400 lb rotor?

Back in college, I found that I learned the most by teaching the other students. We would all be sitting around trying to solve our homework, and for some reason, it just made sense when I tried to help others figure it out, even not knowing it too well yet... go figure. Aside from that I can't help, as I can't recall actually studying outside of doing my homework. Good luck!