Building Definition and 919 Threads

I am building a cardboard bridge that is supposed to span 7-9 feet and made of cardboard. I am having trouble however designing the abutments. The bridge will simply be placed on a table (no suspension designs btw) and will have a maximum 10% grade. What will be the best way to design the...

Hey. I am trying to build a circuit which would switch on/off another device. So far I have tried using an IR LED on the controller and with a phototransistor on the load device (which has it's own batteries), but I cannot figure out how to get it to work. I do not need complicated signals...

http://www.machineguardsolutions.com/images/lightcurtain2.jpg A light curtain seems like a basic communication system setup (TX & RX). But what kind of signal are you trying to send and receive? How should the receiving end get processed? How do you deal with crosstalk from using...

I am having trouble understanding a building collapse. According to NIST, on 9/11 WTC7 collapsed after fire weakened its structural steel. They have however admitted that WTC7 fell for 2.25 seconds at free fall. (http://wtc.nist.gov/NCSTAR1/PDF/NCSTAR%201A.pdf) However isn't all the...

Hi, i was just wondering with this question because I'm unsure if I am supposed to add both kinetic and gravitation energy into this answer? thanks. 1 A crane on a building site lifts an 8.00 × 102 kg load from ground level to a vertical height of 90.0 m at a constant speed of 2.00 m s–1...

Building a matrix using "while" loops? (MATLAB) Hello Here is my code: i = 1; j = 1; S = zeros(11,11); while i < 12 while j < 12 S(i,j) = Test1(a(i,j),b(i,j),c(i,j)); j = j + 1; end i = i + 1; end a,b,c are all 11x11 matrices and Test1 is a...

Hello, I was wondering if anyone knew where you could find a good circuit diagram for building your own PSU. I am looking something that would maybe go up to 15 volts or so, just for doing some testing etc at home. I did a quick search here and didn't find anything. Thanks in...

I have recently come up with an idea about trying to build an apparatus to run some gravitational wave experiments. Now I am still a novice so I wrote Professor Scott Hughes about my idea, he provided me with the mathematical equations that basically show the experiment is impossible. I will...

Building a car in AP Physics, Need Suggestions! Homework Statement Hello, I am in need of suggestions on a project that was recently assigned to my AP Physics class. The challenge was to make a "Tank" (any vehicle) that will go down a ramp, shoot a projectile over a 1.5ft wall, and go back up...

I think I saw a documentary on TV a while back about the thought of building a bridge between Alaska and Russia. The largest bridge ever built. Do you think that this could actually be done in terms of modern structural engineering? I would imagine that such a bridge would become quite a...

Hi all, I wanted some advice on my research-advisor. I was fortunate to have enjoyed a nice night in town with my research-advisor and his girlfriend. He insisted on paying for everything, and he did. I was quite grateful, and have been wondering about a way to return the favour, and/or conduct...

Hello! I recently purchased a basic 6-inch Equatorial Reflector telescope. I bought it because I loved doing astronomy with large binoculars, and I assumed the next step was a small reflector telescope. However, I find myself barely using the new scope because the bulky Equatorial mount is...

i have to build a vehicle that can transport a battery 7 meters in a straight line as fast as possible using the potential enerygy of no more than two kilograms falling from a maximum height of 80.0 cm. i want to build this brake: http://www.scioly.org/w/images/1/19/SC-brake2diag.gif...

we have to build vehicle that can transport a d cell battery 7 meters as fast as possible using the potential energy of no more than 2 kilograms falling from 80cm. we want to use this design: http://www.scioly.org/w/images/6/69/SC-brake3diag.gif...

HI, I have builded a tube buggy out of square 1"1/2 x.085 and was told that it was unsafe so I'm looking into it. Was my design unsafe? My question is round stronger then square if so how much? Question 2 dose welding weaken the steel? Question 3 if round is stronger how much stronger is it...

Basically I got in trouble at college for going onto my dorm roof to get my frisbee so what I have to do is write a 3 page paper about what would happen to someone if they fell off of a 4 story building (17 meters tall). Obviously they would die more times than not. But I need to discuss what...

I was just wondering about any equations that would play a part in this situation. Obviously gravity plays a role but like calculating the force you'd hit the ground at like the force in pounds or something anything really is what I need it's just a general question. Preferably a 4 story...

Homework Statement A 120 kg man jumps off of a 5 story building (~15 meters). How much force is acted upon his body once he reaches the bottom? Will he break any bones?Homework Equations X = (1/2)at^2 (since initial displacement and initial velocity are zero) so therefore: a = 2x/t^2 F= ma The...

I KNOW that this has been asked many times before so I will put it in a way that is not as similar as the rest. My true goal is a bit far fetched so I will just say that I would like to build a time machine. What my question is, which should I study the most, and mainly in college because I am a...

Hello all. I am looking to build a new PC. I really know very little about computers, but since my degree seems to be leading me into the computational realm, that will need to change quickly. Instead of just *building* a PC and going through the motions, I would really like to *learn* what...

hey all, for a science league competition, my team-mates and I are tasked with building a turbine that will draw as much power from a box-fan as possible. Every team has been given an identical motor and the rules specify that we can't modify the motor at all. I've asked around and it seems...

Hi guys. I'm doing a high school project for AP Calc BC. We're supposed to build a 3-D solid using Riemann approximations. Basically, we have to build an object using solely rectangular prisms, or circles. Prompt: Make a physical model of a solid with a known cross-section. For example, let's...

Im not sure if this should go here, but. . . Im building a motion detector. I have the breadboard hooked up the following way using an op amp, a potentiometer, photocells, resistor and led. http://img6.imageshack.us/i/breadboard.jpg/ So it seems to work fine, but I wanted to...

I need to build a toothpick model that can hold a 16 pound bowling ball. I have no idea where to begin, does anyone know of somewhere I can find a tutorial or something?

Homework Statement I need to build a telescope from two magnifying lens, one is 2x the other is 5x. First I need to give the total magnification possible, state which lens to use as the objective and finally to state the length of the telescope. Homework Equations l Ml = Fo/Fe total...

Hello All, I'm currently working on a project to help with a local spaghetti bridge contest. I'm trying to build a scale of sorts from a plate that is supported at each end. Picture a bracket "[" but with the two legs on the ground. I'm using strain gages on the bottom in the shape of...

Hi physics folks- Every year for the past 3 years, I have built an ice rink in my back yard. Unfortunately, I do not have the flattest back yard, in fact it has quite a downward slope and then a steep uphill slope. But, I'm determined the make the biggest rink I can reasonably make, given...

I have a few questions. 1. Which programming language should I use? I am thinking of using C++. I know assembly but am not very good at it, so I am trying to avoid assembly. 2. Which program should i use to compile the PIC code? I am thinking of using MPLAB IDE. Is it sufficient/ok? 3...

If a ball is thrown upwards, another straight out, and another downwards, which will reach the ground with the highest velocity? After thinking about this for a while my conclusion is that they all will have the same velocity since they all have the same initial gravitational potential energy...

I need to make a bridge using Balsa Wood, but I can't decide whether to use the Howe or Pratt Truss. Requirements maximum mass of 25 grams maximum test load will be 15kg must allow a 5.0 (∼2”) cm cube to pass along the roadway without touching the structure must be an opening at the...

Homework Statement Hey I'm building a graph of period squared vs. mass for simple harmonic motion finding the slope and getting K for a spring. since T^2 = ((4*pi^2)/k)m the slope is (4*pi^2)/k so I get my slope from my graph and it has an uncertainty of +- 0.2 to get K we...

Hello forum , i want to ask you a simple question , i am building a circuit on a bread board, the circuit is an H bridge 8A , is normal bread board can handle this current or the connection inside the bread board will be in not safe mode ? Thanks for reply, Have a nice day

Homework Statement A vertical building was built on a horizontal plane. The plane is then tilted to A=(0,0,0) B=(1,2,0) and C=(0,3,1). By what angle (in radians) does the building now deviate from the vertical? Homework Equations Dot Product Cross Product The Attempt at a...

Hi I hope that this won't be treated like spam or something. I just used search engine to find place where I can find people who may be interested to help me building something that I call "valve library". I started small website with intention to create online place where You can find all...

Homework Statement A 72 kg person escapes from a burning building by jumping from a window 30 m above a catching net. The acceleration of gravity is 9.81 m/s2. Assuming that air resistance is simply a constant 88 N force on the person during the fall, determine the person’s velocity just...

This is not homework, although I am an EE student. If the solution is cool/complex enough, this might become a design project, although it'll most likely end up as something to do over the summer. some time ago, I purchased a motorized doggie door. The dog wore a high frequency sound...

I am very interested in engineering, so I decided to build a mousetrap vehicle. I want my vehicle to reach 5 meters and return back to its original destination by itself. I need help constructing this system to accomplish this goal. Is there any way to build it with 2 mousetrap at most?

Homework Statement a spotlight won the ground shines on a wall 12 m away if am man 2 m tall walks from the spotlight towards the building at a speed of 1.6 m/s how fast is the length of his shadow on the building decreasing when he si 4 m from the building? Homework Equations using...

Homework Statement At the top of the building that's 65m high, a guy throws a ball upward. The ball comes back down and hits the ground in 4 seconds. A)What is the initial velocity when the guy threw the ball? B)What is the highest height of the ball? C)At what time does the ball comes...

I have already built most of the chopper but am trying to add an accelerometer. Let's say the blade is rotating at 600rpm, this is causing vibrations throughout the vehicle at 10hz. I want to make a compartment which doesn't feel most of these vibrations. I'm thinking of building something using...

heyy guys i am participating in an aero competition in which the problem stmt is to design an acrobatic hand launched rc plane of wingspan 3 ft max which can perform stunts like a vertical loop, sharp turns and 360 roll...can you please tell me how to begin designing this aircraft...i...

1. A 0.43 kg rock is projected from the edge of the top of a building with an initial velocity of 9.2 m/s at an angle 45◦ above the horizontal. Due to gravity, the rock strikes the ground at a horizontal distance of 14.9 m from the base of the building. How tall is the building? Assume the...

hi guys i want to make a device consists of - a motor - stick (60 cm long, 0.4 Kg) - remote control - step motor to pull a rope -buttries the idea is the main motor rotates the stick for seconds or for a minute. and the step motor pulls the rope 360 or 720 degrees. and all these...

Homework Statement A rock is projected from the edge of the top of a building with an initial velocity of 18.4 m/s at an angle of 35◦ above the horizontal. The rock strikes the ground a horizontal distance of 96 m from the base of the building. The acceleration of gravity is 9.8 m/s2 ...

Since the SABLE project broke on slashdot and youtube, I've been kind of keeping an eye on the tech, and science these average Joe's put into it. (I'm one of these average Joe's). For those not familiar what these projects, here's an overview. The SABLE and BEAR projects basically strap a...

I would like to construct this thing: http://www.thereminworld.com/pics/schematics/simple.jpg However, I am unsure of the chips to use: *Can I assume the 4093 is going to be a nand quad gate? (say: http://www.thereminworld.com/pics/schematics/simple.jpg) For the 4077, what about this...

So apparently Michio Kaku built a 2.3-million-electron-volt particle accelerator in his parents' garage; once Harvard University found out about this they granted him admission. I'd like to go to Harvard. So if I were to build a particle accelerator would I be breaking any laws, or is it...

A golf ball is released from rest from the top of a very tall building. Choose a coordinate system whose origin is at the starting point of the ball, and whose y-axis points vertically upward. The acceleration of gravity is 9.8 m/s 2 . Neglecting air resistance, calculate the ve-...

Homework Statement Please help me with this problem: Rock is thrown straight up with a velocity of 24 m/s from the edge of a building. The rock is moving at 43 m/s when it strikes the ground. Acceleration is 9.8 m/s^2. How tall is the building? I know it involves the equations of...

dman gman vman zman are leaving in a 4 floor building one on each floor. its known that gman is leaving under vman and dman. zman is leaves under dman and above vman. on which floor each one of the persons leave?