Engineering - November 2007

A light dimmer is a possible application of a series RL-circuit. Assume for simplicity that the resistance of the lightbulb is constant with R=100 Ohm. For a dimmer, the bulb is connected in series with a variable inductance L.
The circuit is connected to a wall outlet with 115V AC oscillating at 60 Hz. What range of L is needed if it is desired
to vary average power from 30W to 100W?

2007-11-22 12:00:28 · 2 answers · asked by Ali Ahmed 2

I heard osmething baout using PVC pipe to make a flute. but the PVC has to be plastic or something.

can anyone tell me mroe baout this in simplet terms?

2007-11-22 11:18:54 · 3 answers · asked by Anonymous

why not just cool the engine with the air directly like in the early vw beetles?

2007-11-22 09:03:17 · 9 answers · asked by Anonymous

2007-11-22 07:53:58 · 8 answers · asked by henryfroch 1

I need help.im in 9th grade and i need to do a research project that has to be pretty advanced.right now im going to do an experiment where im take nails comparing them to see which one rust fast like,one will be a regualr steel one,one will be painted,one will be galvanized and there will two nails used together as cathode protection.how can i make it better?i need answeres asap,please!!!!!!!!!!!!!!!!!!!!!!!!
16 hours ago - 3 days left to answer.

2007-11-22 07:18:17 · 2 answers · asked by Speeding D 4

i have an invention but cant find an engineer to design and build, who wont steal my idea

2007-11-22 07:01:06 · 4 answers · asked by vivid 1

2007-11-22 06:13:58 · 5 answers · asked by Anonymous

2007-11-22 04:48:50 · 1 answers · asked by Anonymous

I'm planning on making a geodesic globe for a art class. I'm likely going to do a 320 sided version, as the next biggest one is 1280 sides (correct me if i'm wrong on that). But i need to figure out what size to cut the triangles, is there a basic formula to figure it out? If it helps, i'm likely going to go for something basketball sized or the same size as a standard globe, since i'll likely use one as a shell and cover it with the triangles.

2007-11-22 02:43:06 · 2 answers · asked by Zonglars 1

What is the main role that the frequency plays in passive filter circuits?

2007-11-22 02:31:35 · 5 answers · asked by David Junior 3

2007-11-22 01:40:36 · 4 answers · asked by Ahmad M. Alawi 3

what is the ampere of 1 1.5V AA battery

2007-11-21 22:38:04 · 6 answers · asked by dennis j 1

2007-11-21 19:04:22 · 3 answers · asked by Anonymous

I saw a project where you can incorporate a serial GPS device with an LCD on a microcontroller I believe. It seems interesting to try but I was wondering if you had to pay some company monthly to provide your chip with GPS information? Or is it just out there and avaliable to everyone? Actually my main goal is to have GPS on a budget as I get lost very easily in my own city and do not feel like paying the $80 per month for a GPS cell phone like I had planned. Any thoughts or suggestions?

2007-11-21 18:54:23 · 6 answers · asked by Jerome54 5

2007-11-21 18:04:30 · 1 answers · asked by Anonymous

hi plz tell me how can we step up the current (Ampere)

2007-11-21 17:26:35 · 3 answers · asked by cu 1

For solubility of a liquid in a liquid, I know that changing the temperature won't affect it much. But why won't it affect it much? Like why is the changing of temperature ineffective to the solubility?

Thanks.

2007-11-21 14:52:34 · 1 answers · asked by Anonymous

would the Youngs modulus touch the temperature axis ie become zero when it reaches the meltingpoint ??

2007-11-21 14:39:26 · 1 answers · asked by T3RR0Rist - 1

Just realized. I'm already 14 now. I am terrible at math. Have I been chasing the wrong dream this entire time. It feels terrible to face the truth, but I'm just NOT GOOD AT MATH.

I've always been dreaming of making a salary with 6 digits. Now that it is nearly impossible for me to become an engineer, are there any other suggestions? Its gotten so bad, that I can't sleep anymore. :(

On the other hand, I've been told that I have talents in the following:

Music
Art
Impromptu Speech / Debate

Its too ambiguous! I need an expert opinion on my career path.

2007-11-21 14:16:36 · 9 answers · asked by Butterloaf 1

2007-11-21 14:02:48 · 1 answers · asked by Fitri 1

2007-11-21 12:33:41 · 3 answers · asked by mugen_ex 1

1. Give an example of an open cover of (-1, 1] which does not have a finite subcover.

2. Give an example of a function f: (A U B)-->R such that f is uniformly continuous on A and B but not on (A U B). U denotes union and R denotes the set of real numbers.

3. Give an example of two uniformly continuous functions f,g : D -- > R such that f*g is not uniformly continuous. R denotes the set of real numbers.

2007-11-21 10:47:19 · 1 answers · asked by Gabe 3

I have always been interested in electronics and mechanical things, or at least felt a strong connection to technology, but it hasn`t necassarily become a part of my life. I mean, I asked my mom to buy me a Mindstorms set a couple years ago, and I ended up not liking it. Because of my interest I took an inventor`s class where you built contraptions based on physics principles, but I hadn`t enjoyed that either. I love reading about how things work and collecting things like cogs and gears and basically whenever someone mentions "internal combustion engines" I am immediately intrigued. I will admit it: I have fallen in love with an electrical appliance before, I have spent hours at a time taking apart a computer keyboard, and I have snuck into the Tech-ed department(even though I wasn`t supposed to be there) just to look at the tools and inventions other students had made. What`s wrong with me?? Who am I kidding- I hated working with tools. I`m not a "mechanical" person.

2007-11-21 10:00:05 · 5 answers · asked by Anonymous

I need to know how many gallons or something of water a normal water pipe can hold.. Its for a science essay =/

2007-11-21 09:22:03 · 4 answers · asked by Anonymous

2007-11-21 09:03:34 · 4 answers · asked by jams 1

When 0.404 g of compound X is burned com-
pletely in a bomb calorimeter containing 3000
g of water, a temperature rise of 0.428 C is
observed. What is delta(U) for the combustion
of compound X? The hardware component of
the calorimeter has a heat capacity of 3.54
kJ/C. The specific heat of water is 4.184
J/g*C, and the MW of X is 56.0 g/mol. An-
swer in units of kJ=mol.

2007-11-21 08:12:12 · 1 answers · asked by rachlopez88 1

I remember working at my uncles shop ( as an electronics technician ) for a year around 8 years ago

these were my job duties

I had to read and interpret mechanical, optical, and electrical specifications.I used multi-meters, digital oscilloscopes, DVM and function generators
I tested analog and digital circuits and generated test reports in MS Word, MS Excel and MS PowerPoint.

These are the job descriptions that I could put in words.
But i can't remember why i was testing , reading and measuring all these voltages and so on and so forth .

I dn't know if he was an evil genius working on world domination or if he was working on a project that relates to world domination ?

the bad thing is that i need to add this to my resume ,and i wanna write what was it that i was working "ON" .

what do you think , in your mind , was I working on ?
any help would make me glad .
Thanks.

2007-11-21 08:10:52 · 8 answers · asked by sum142121 1

The blocks are so big even todays technology could not move them. How could this be?

2007-11-21 07:35:32 · 5 answers · asked by Anonymous

2007-11-21 04:27:08 · 5 answers · asked by glyn r 1

2007-11-21 02:03:59 · 3 answers · asked by bdunn22003 2