## Search found 709 matches

Thu Sep 01, 2011 6:46 am UTC
Forum: Mathematics
Topic: Lines or curves
Replies: 10
Views: 1811

### Re: Lines or curves

pizzazz wrote:A curve is just infinitely many infinitesimally short lines :-p

O rly?

After spending the last couple weeks trying to numerically simulate a very non-linear system, I'd kill for some nice, simple lines.
Mon Aug 01, 2011 6:01 am UTC
Forum: Mathematics
Topic: Help an engineer learn complex analysis
Replies: 8
Views: 1775

### Re: Help an engineer learn complex analysis

Thank you, that seems like another useful way to look at these things.
Mon Aug 01, 2011 5:43 am UTC
Forum: Mathematics
Topic: Help an engineer learn complex analysis
Replies: 8
Views: 1775

### Re: Help an engineer learn complex analysis

When you say "flip it to the opposite sense", do you mean that the cross-product of the unit vectors along two curves through a point will be the same under a conformal mapping, but reverse in direction under an anti-conformal mapping?
Mon Aug 01, 2011 3:56 am UTC
Forum: Mathematics
Topic: Help an engineer learn complex analysis
Replies: 8
Views: 1775

### Re: Help an engineer learn complex analysis

Thank you, that was a very interpretation.
Mon Aug 01, 2011 1:26 am UTC
Forum: Mathematics
Topic: Help an engineer learn complex analysis
Replies: 8
Views: 1775

### Help an engineer learn complex analysis

Hello, math forum. I'm an engineer who's trying to teach himself complex analysis in preparation for a class in the fall. I'm using the online notes for the class (which are essentially the textbook) and doing some problems and proofs. My goal is not to gain a complete, can-prove-everything understa...
Mon May 30, 2011 10:55 pm UTC
Forum: Science
Topic: Help with A Heat Transfer problem from my study guide
Replies: 2
Views: 661

### Re: Help with A Heat Transfer problem from my study guide

How can there be direct heat transfer from 1 to 3? There should be a constant amount of q''12 and q''32, and a q''21 and q''23 which are functions of T2. Just use energy conservation for steady state (energy in = energy out) on the middle plate.
Wed May 25, 2011 7:13 pm UTC
Forum: School
Replies: 157
Views: 36053

Zcorp wrote:Oh and almost none of the most successful private schools Track and none of the big name in charter schools Track. Sure they have selection bias, but it this is compelling evidence the problem is largely environmental.

None of them offer AP classes? Cite please?
Wed May 25, 2011 7:11 am UTC
Forum: School
Replies: 157
Views: 36053

Okay, I can accept that the BS once-a-week pull-out programs in elementary school do "little to nothing to benefit" their participants, but advocating getting rid of AP classes, even if they are open-enrollment, is going too far. Personally, AP classes saved me about \$15,000 by allowing me...
Wed May 25, 2011 4:51 am UTC
Forum: School
Replies: 157
Views: 36053

Zcorp, I'm a little unclear on the exact meaning of "Tracking." Could you please say whether each of the following is "Tracking" and whether you support it? -Placing special education students in their own class -Placing proven delinquents or violent offenders in their own school...
Wed May 11, 2011 2:38 pm UTC
Forum: School
Replies: 43
Views: 6218

### Re: Alternative test grading system?

KestrelLowing wrote:Oh, and I also don't have any integration tables memorized.

So you go back to the definition of the derivative to figure out the antiderivative of x, or x2, or 1/x? For that matter, how do you know the definition of a derivative, if you haven't memorized it?
Mon May 09, 2011 11:33 pm UTC
Forum: Science
Topic: Carbon (dioxide and graphite)
Replies: 43
Views: 6396

### Re: Carbon (dioxide and graphite)

That implies that diamond is unstable. It is. If you look at your diamond close enough, you might see a few atoms reorganize themselves into graphite before the heat death of the universe. (BTW, does anyone have data on the kinetics of this transformation? I'd love to try and figure out an actual n...
Fri Apr 29, 2011 2:59 am UTC
Forum: Science
Topic: How much air is needed for wind?
Replies: 25
Views: 3715

### Re: How much air is needed for wind?

Inertia keeps the air mass from rotating as you go upward from the surface, except where it is in direct contact with the rotating cylinder. Let me introduce to my friend viscosity . Viscous fluid behavior is described by the Navier-Stokes Equations. Solving the Navier-Stokes equation in cylindrica...
Wed Apr 27, 2011 2:44 am UTC
Forum: Science
Topic: Using Bernoulli's equation
Replies: 12
Views: 1594

### Re: Using Bernoulli's equation

One thing to note: when we assume incompressible inviscid flow, what we solve for is the mass flow rate, not the flow velocity. As it turns out, the only thing that determines our flow rate is the pressure difference, and not the size of the hole. I don't understand how that could be the case. It m...
Tue Apr 19, 2011 4:26 pm UTC
Forum: School
Topic: Calc or Stats
Replies: 24
Views: 5623

### Re: Calc or Stats

torgos wrote:calculus, which will be integral to a good deal of work in most STEM fields.

I see what you did there.

Why not have both? If you move algebra to 8th grade in place of whatever the hell math is taught in 8th grade now, there is plenty of time to take stats and calc in high school.
Tue Apr 19, 2011 12:59 am UTC
Forum: Science
Topic: Estimating Alcohol Content With Density Alone
Replies: 10
Views: 1997

### Re: Estimating Alcohol Content With Density Alone

if you assume water and alcohol are the only 2 things present, then your solution should be X% alcohol and (100-X)% water. You can solve for X by setting Y equal to your final measured density and solving Y= (X*density of alcohol)+((100-X)*density of water). If anything besides water and alcohol ar...
Mon Apr 11, 2011 10:19 pm UTC
Forum: School
Topic: Humanities in STEM Majors
Replies: 40
Views: 5197

### Re: Humanities in STEM Majors

If you don't want to enroll non-humanities courses, don't go to a university, and go to a technical institute of some sort instead that doesn't require this. University education does mean well rounded education. University education is also specialized education. For a constant time-to-graduate, t...
Fri Apr 08, 2011 8:09 pm UTC
Forum: Science
Topic: Acoustics: principles, resources?
Replies: 4
Views: 868

### Re: Acoustics: principles, resources?

By the way, I think you can understand a lot of this stuff intuitively without studying it all rigorously. For example, a common theme is that increasing stiffness increases frequency, and decreasing stiffness decreases frequency. This is evident in plates, beams, strings (where the stiffness equiva...
Fri Apr 08, 2011 7:39 pm UTC
Forum: Science
Topic: Conceptional double-pulley problem (Tension)
Replies: 15
Views: 3211

### Re: Conceptional double-pulley problem (Tension)

No, it's definitely a third. The FBD has already been provided so just use sum(f)=0 to find T. System is accelerating, isn't it? There's a big acceleration vector on the right hand side pointing upward. Sorry, I was responding to eSOANEM right above me, who was quoting tooyoo, who was talking about...
Thu Apr 07, 2011 3:55 pm UTC
Forum: Science
Topic: Skydiver
Replies: 39
Views: 4160

### Re: Skydiver

If aiming for land you might survive due to sheer dumb luck, such as landing 4 feet snow pile on top of a large patch of scrub, growing on very marshy land. It's exceedingly unlikely, but it's been known to happen. I have trouble seeing how all that would be softer than water. I guess the air force...
Wed Apr 06, 2011 11:21 pm UTC
Forum: Science
Topic: Acoustics: principles, resources?
Replies: 4
Views: 868

### Re: Acoustics: principles, resources?

For things like a ringing bell, you want to look at structural dynamics. The simplest case of structural dynamics is the vibrating string . If you get to the point where you can perform modal analysis on a string, then move on to beam bending dynamics . From there, you can go to plate dynamics , whi...
Wed Apr 06, 2011 5:51 pm UTC
Forum: Science
Topic: Conceptional double-pulley problem (Tension)
Replies: 15
Views: 3211

### Re: Conceptional double-pulley problem (Tension)

No, it's definitely a third. The FBD has already been provided so just use sum(f)=0 to find T.
Tue Apr 05, 2011 3:15 pm UTC
Forum: School
Topic: How hard is Georgia Tech?
Replies: 9
Views: 3785

### Re: How hard is Georgia Tech?

It depends on what you are majoring in. For engineering, Georgia Tech is hard, but probably no harder than schools with similar rankings. I think you are correct that the admissions are lenient enough that we get a lot of people who aren't prepared for such a rigorous curriculum. The kind of people ...
Tue Apr 05, 2011 2:23 am UTC
Forum: Science
Topic: [Homework] BVP Project Ideas
Replies: 2
Views: 707

### Re: [Homework] BVP Project Ideas

How about beam bending? It's probably different enough from the wave equation to satisfy your professor, but close enough that you'll know what to do.
Thu Mar 31, 2011 3:45 am UTC
Forum: School
Replies: 16
Views: 2882

If I were you, it would be School B hands-down. When you graduate, you will have access to the resources and connections of both schools. Having to TA while doing interesting research is more appealing to me than being an RA on an uninteresting project.
Thu Mar 31, 2011 3:32 am UTC
Forum: Science
Topic: Microgravity
Replies: 5
Views: 1010

### Re: Microgravity

Do you mean that the direction of apparent gravity never changes at all, in any direction? Or that it never points to the side? In the first case, that would be very hard to accomplish. In the second, that just means that the plane is making coordinated turns , i.e. banking the plane so that the app...
Tue Mar 22, 2011 3:53 am UTC
Forum: Science
Topic: Variation of the dreaded airplane/conveyor belt...
Replies: 29
Views: 6680

### Re: Variation of the dreaded airplane/conveyor belt...

The channel wing: a propeller plane designed to take off vertically.
Tue Mar 01, 2011 5:04 am UTC
Forum: School
Topic: Last-minute university application apprehension
Replies: 8
Views: 1901

### Re: Last-minute university application apprehension

Dude, calm down. You're applying to UF, not Harvard. If they ask what you've been doing, tell them what you've been doing. "Full-time employment, 20XX-20XX, XXX Community College 20XX-20XX" is probably exactly what they're looking for.
Fri Feb 25, 2011 11:01 pm UTC
Forum: School
Replies: 12
Views: 2488

What do you want to specialize in for grad school?
Wed Feb 23, 2011 3:33 pm UTC
Forum: School
Topic: Grade Inflation in the US
Replies: 105
Views: 13999

### Re: Grade Inflation in the US

I agree that you guys are being a bit alarmist. Technical fields tend to have lower grade inflation, since they have strict curriculum standards and professors who spend most of their time researching. In addition, hiring decisions are usually made on the basis of work/research experience in additio...
Mon Feb 21, 2011 11:02 pm UTC
Forum: Science
Topic: Civilian Avionics
Replies: 90
Views: 8608

### Re: Civilian Avionics

Mon Feb 21, 2011 4:50 pm UTC
Forum: Science
Topic: Aerodynamic rotor (optimal number of blades)
Replies: 17
Views: 2158

### Re: Aerodynamic rotor (optimal number of blades)

The wikipedia page you linked states that there is a "diminishing return" and goes on to claim that there is a 6% increase in efficiency when increasing blade count from 1 to 2 which confuses me as i would have thought that having twice the blade area would mean twice the power. Remember ...
Mon Feb 21, 2011 3:49 pm UTC
Forum: Science
Topic: Aerodynamic rotor (optimal number of blades)
Replies: 17
Views: 2158

### Re: Aerodynamic rotor (optimal number of blades)

I can't find anything specifically about blade number in my textbooks, but wikipedia has a couple of leads. The article on wind turbines has an uncited section which gives a plausible explanation of the various trade-offs. The article on propellers links to a 1943 Popular Science Article which brief...
Mon Feb 21, 2011 10:24 am UTC
Forum: Science
Topic: Civilian Avionics
Replies: 90
Views: 8608

### Re: Civilian Avionics

I'm going to ask a total newbie question. Will an off the shelf turbine even work at transsonic or supersonic speeds? You discussed a lot about how aerodynamics work differently at those speeds, and how you have to take that into account when designing the plane itself, but you seem to assume the e...
Mon Feb 21, 2011 7:36 am UTC
Forum: Science
Topic: Civilian Avionics
Replies: 90
Views: 8608

### Re: Civilian Avionics

You should just be able to use a flange on the after-burner to connect it to the end of the turbine. Nothing especially heavy or complicated about that Well, there's no flange on the turbine exhaust nozzle, so you're going to have to make a flange for it and weld the flange to the nozzle. They're g...
Wed Jan 26, 2011 6:34 pm UTC
Forum: Science
Topic: Thermodynamics Questions
Replies: 13
Views: 2461

### Re: Thermodynamics Questions

If the problem didn't state that the expansion/compression was isothermal, then the best assumption would be that the process is isentropic (adiabatic and reversible), and P*V^gamma would be constant. However, isothermal compression/expansion of a gas cannot be adiabatic. There is a pretty obvious w...
Wed Jan 26, 2011 12:54 am UTC
Forum: Science
Topic: Thermodynamics Questions
Replies: 13
Views: 2461

### Re: Thermodynamics Questions

The problem says "Assuming that the temperature of the gas remains constant." When you're doing work on a fluid, adiabatic != isothermal.
Tue Jan 25, 2011 5:33 am UTC
Forum: Science
Topic: Thermodynamics Questions
Replies: 13
Views: 2461

### Re: Thermodynamics Questions

ChicagoPianoTuner wrote:Just figured it out. Need to use PV^gamma=constant. Taylor expand and then use N2L. Post again if you're still having trouble. Tricky problem!

That would be isentropic; the problem says isothermal.
Mon Jan 24, 2011 11:42 pm UTC
Forum: Science
Topic: Thermodynamics Questions
Replies: 13
Views: 2461

### Re: Thermodynamics Questions

Just write the volume in each case as cross-sectional area (A) times the relevant height. Work through the problem symbolically, and the area should cancel out. Pretty sure the area doesn't cancel out, but you can indeed solve for it given the initial conditions: you know the moles of gas at STP, h...
Mon Jan 24, 2011 2:37 am UTC
Forum: Science
Topic: Circuit Problem
Replies: 3
Views: 758

### Re: Circuit Problem

I see 3 unknowns and 3 equations. Am I missing something?
Mon Jan 24, 2011 12:55 am UTC
Forum: Science
Topic: Thermodynamics Questions
Replies: 13
Views: 2461

### Re: Thermodynamics Questions

If you define the buoyant force as the integrated pressure force over the surface of the object, then the buoyant force is equal in magnitude to the weight of the displaced fluid. In that case, the problem is here: Bouyant force [F(b)] - envelope weight - load = 27.0 N There's a weight you're forget...