Building Definition and 891 Threads

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I hope I am posting this on the right section... In my Environmental Science Class, we are to design and build a solar oven(without using solar panels!). We will be baking a cookie. Me, being a "mathematician", remembered something about a parabola, that if light ray hits anywhere on...

ive done a search on google and found a lot of things about supplements and muscle building etc. im wondering what factors affect the amount of testosterone in your body? ive read working large groups of muscles increases it, and also exposure to sunlight (apparently) can anyone...

Hi, I am supposed to build a controller for a 5 wire servo. I'm having trouble finding information online that appeals to electrical engineering folks. What are the 5 wires? I suspect there is power and ground, but that leaves 3 unknown connections :eek: I have a basic understanding...

This is not homework, I'm just curious. Perhaps it belongs in the Engineering Forum, but the last one of these I posted there just got left in the dust. I have a rather specific question to ask those of you who are familiar with paper airplane building/structure/dynamics. How would I go about...

Currently I am doing a straw building project with a group and we are in need of an interview from a real life engineer. So if anyone can help me with my design on our Girder Bridge then it would be appreciated.

Homework Statement Spider-Man steps from the top of a tall building. He falls freely from rest to the ground a distance of h. He falls a distance of h/4 in the last 1 second of his fall. What is h? Homework Equations All kinematic equations with free fall. The Attempt at a Solution...

Homework Statement A projectile is fired from the edige of a building with initial velocity of v0=10 m/s at an angle of 45 degrees. The rojectile rises and then lands oln ground at point P as shown, which is 35.4 meters away from the base of building. A) Find the Y component of the projectile's...

all I really need right now is a 5 pound small weight that can fit in a spoon but I don't think there is anything that size that can fit in a spoon that would be lying around a house so what is a good projectile for the trebuchet the size of this one which will have a base of 75cm^2 or about 38...

Homework Statement I'm studying logic gates and trying to create my first one. Homework Equations 3. In a TV programme, the panel votes on new performers. The panel consists of a Chairman (C) and three others (X, Y and Z) who each press a button to register their vote. The SUCCESS light is...

As a summer project I was thinking of building an entirely mechanical Turing machine - possibly with Lego. Has anyone attempted this? Does anyone have any advice on how to design this? Thanks.

Hi everyone, Can anyone tell me how to build simple solar energy generator for kid of age 5 – 7 year? Please tell and send me with some drawing. Thank you very much in advance Huygen

First post here, although I could eyeball this project I have been stumped as to how it would be calculated. I haven't been in a geometry class for nearly a decade so this really brought to light how much I have forgot. I need to find how tall a board would be cut if it descends at a certain...

i need help minimizing the cost of this building? immediate help pleasez A university has decided to build a new, creative dorm! After a contest to determine the shape, it was decided that the dorm would be in the shape of an airplane hangar that has semicircular ends. There is an additional...

Hello all! I am building an effects pedal for my guitar (dont have a choice, I spent all the money I was saving on the guitar). Since electronic components are cheap, for once, I am glad I am studying EE. At first I thought I'd design the circuits myself, but after doing a bit of research, I...

i want to build a matrix that can solve cross product multiplication of 2 vectors, building a matrix A so that detA=PxS A= \hat{i} \hat{j} \hat{k} P1 P2 P3 S1 S2 S3 how do i build a code so that my det will give me a vector answer?

Is it in any way possible to build a 10 watt (battery powered) handheld laser?

I have limited hardware components I can use for this obstacle. Let's say I have precision rectified the input heartbeat signal into a square wave... I am trying to count the number of squarewaves/heartbeats and display them on two 7-segment displays refreshing every 15 seconds... I can only...

Homework Statement I'm building a hovercraft, and I'm familiar with how to calculate center of mass--however, there's something that will be sitting on the surface of the hovercraft that's throwing me off. I just can't seem to get it to work. I'm just trying to find what the mass would be at...

Hi everyone, I'm new to this forum. I'm working on a senior project where we are using ultrasonic transducers at very high frequencies. Problem is we only have some weaker 25V power supplies to drive the transducers. To fix this problem we were going to purchase a power amplifier but due to...

1. How to attach my wheel, plastic lids with rubber bands around, and axle, a wooden dowel rod 5/8 in diameter, to the car body, which is a board of wood? I used a wood block and attached the too the body and drilled a hole big enough to slide the axle. I also put a piece of aluminum around...

the instructions for building it is that we can't use anything for the car that would be used in its original purpose so like for wheels we couldn't use actual wheels. I want to make it pretty big but light at the same time and the goal is to have a car with fast acceleration and that can go...

also, i am unsure about the units...are the above ones ok? as in the website had these units [ KWh/m^2/ hello everyone! i know that solar collectors are commonplace in many parts of the world (tho not mine) so this might sound a bit stupid... anyway, i wanted to make (actually build) a solar...

We are trying to build a bridge made from paper, water based glue and cotton strings. The bridge must be able to hold 5kg; however, we would like it to hold more weight. The weight of the bridge should also be taken into consideration. So we came up with numerous designs and we finally...

I'm fairly experienced with computer hardware and software, but I've been out of the game for awhile in terms of buying new machines. I'm looking to buy/build a computer for academic work (computational astrophysics). I have about $2000 to spend, and I really want to maximize the power that this...

I'm trying to build a betatron with the electron gun from a television. What do you think would be the best material for the tube of the electron gun? Also, do the electrons need to be accelerated further after being emitted from the electron gun, or do I just need to guide it with coils...

Homework Statement Need to heat 30mL of water from 20C to 40C in 1 min(60s). Using 6V battery and Nickel Chromium alloy Nichrome wire that has a resistivityabout 10^-6 ohms/meter. So you use the battery and the wire to build a water heater. Batter has no internal resistance. Homework...

I'm not understanding something very basic here. I know what voltage drop is. At least I thought I did. Here is a question: Assume you have a power supply in a control panel of a building. 500 feet away is the load device. When doing voltage drop calculations for the wire (500 feet...

About thirty years ago I was experimenting with some electrical/magnetic devices and found that a machine called a Kirlian machine would light up the path (coronal discharge) of magnetic fields and so I could visually see the presence of a magnet field and therefore an electrical current as it...

I also have a membership at scienceforums.net and posted this to try to figure out what went wrong, but my post has been up for a week with 100 views and 2 replys both saying that they have no idea what I'm talking about. Hopefully I will have better luck here. Quick introduction: I am 16...

Hey I was wondering if you all could help me. I need to build something that will move a rod of wood back and forth in a fashion similar to a musical metronome. I am hopeing to make it for under 50 dollars and need it to go about 200 rpms at min. ____...

Homework Statement Spiderman steps from the top of a tall building. He falls freely from rest to the ground a distance of h. He falls a distance of h/4 in the last interval of time of 1.2 s of his fall. What is the height h of the building? The acceleration is constant -g. Homework...

OK, so I decided to put together a computer, but I'm having some trouble. Hopefully it's of the "you forgot something obvious" variety, rather than "it's broken". The thread is titled as it is because I imagine that if I fix this problem, others will come up I'll also need help with. So I...

I found an old circuit diagram online but have never been able to find it again. Here is what I am trying to do: The three-phase DC motor I am working with is a 4-pole motor. Therefore there is a direct relationship between the frequency between the motors phase-leads, and the current RPM of...

Hi folks, I am new to PF. First I have to apologize for the following english -- it is not my native language. I have problems in understanding the formation of the conduction and valence bands of solids: For example in III-V compound semiconductors both constituents are sp3 hybridized...

so i just survived my first semester at a real college, (transferred from community college), and got my A@# handed to me. I did however pass everything and learned a ton. I learned what real studying is and that I am probably not cut out for grad school, but we shall see. i am curious if its...

I am building a Pinewood Derby car (Just for fun) and I want to make my car REALY areodynamic, but I don't really know the basics of areodynamics. Please help!

Anyone know how to do it? I do not know where to find dee electromagnets, nor do I even have the complete design of his system.

1. Suffer extreme symptoms from Microwave RF emissions cell phones, Wi FI, Cordless computers and RF Routers. 2. The next door neighbour has installed a Uniden DECT that transmits continually 24 hours a day. Our bedroom and the next door neighbours loungeroom is separated by a normal...

I would like to build a particle accelerator as a science project. I know it may be unrealistic, but depending upon the size and complexity that I choose, it should be possible. If anyone could help with the construction process of a small particle accelerator(preferably circular), I would...

Hey PF, I want to resurrect an old robot radio I have sitting around. What exactly is involved with building an AM/FM receiver?

Hi, I've got two related questions. You can decompose a (semisimple) lie algebra into root spaces, each of which are 1-dimensional. If X has root a and Y has root b then [X,Y] has root a+b. If the root space of a+b is not zero (i.e. there is a root a+b) then is it possible for [X,Y] to still...

Hey there PF! I'm currently working on building an Infrared Remote to control a series of triacs. The objective is to create a "remote control power bar". The original plan was to use push button switches to toggle the Q lead of a 4013, each of which houses two switching circuits. Q and NOT-Q...

***Building a pump from scratch, engineering competition*** Hello everyone. I have been entered into a competition. The spec is to build a pump that can pump 30 litres of water a minuet for 30 minuet to a height of 4 meters. The pump has to be built over 3 days (18hours) but i have...

Hi everyone, I want to ask everybody if someone knows a book, or some lecture notes available on the net, to lear how to decompose the Lie Groups in irreps in physical notation, like 8_v \otimes 8_v=1+28+35 that can be found everywhere on books like BB&S or Polchinski. It is really hard...

I found this link and thought it may be of some use to build a power supply. I know that these power supplies can pack around 500W on the right power supplies. Is there anything I should know and be careful of when making this and when playing with smaller electronics...

Homework Statement I need to build a faraday flashlight and I have two problems. Homework Equations (1) When I use a 12V DC motor connected in parallel to a capacitor (16V 2200uf) and then to an LED assembly, I can't get the capacitor to charge. (2) If I wanted to use a magnet and coils...

Could a new universe be built with purley information, i do not know how to explain this question any better without corupting it in some way, may be a lesser question is, is matter, energy purley information.

Homework Statement Suppose a stone is thrown from a 45.0 m tall building at an angle 26.0° below the horizontal. If it strikes the ground 30.3 m away, find the following values. (a) time of flight __________s (b) initial speed _________ m/s (c) speed and angle of the velocity vector...

I'm building a tank circuit and I need to know if a ground connection is needed.