What is Bridge: Definition and 481 Discussions

A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually something that is otherwise difficult or impossible to cross. There are many different designs of bridges, each serving a particular purpose and applicable to different situations. Designs of bridges vary depending on factors such as: the function of the bridge, the nature of the terrain where the bridge is constructed and anchored, and the material used to make it and the funds available to build it.
The earliest bridges were likely made with fallen trees and stepping stones. The Neolithic people built boardwalk bridges across marshland. The Arkadiko Bridge (dating from the 13th century BC, in the Peloponnese) is one of the oldest arch bridges still in existence and use.

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  1. R

    Poor design led to I-35W bridge collapse?

    This image shows the ground supports of the bridge before the collapse: http://www.wmur.com/2007/0802/13805989_240X180.jpg taken from: Nation's Bridges Face Immediate Inspection. Fifth Victim Found; President Bush To Visit Minneapolis UPDATED: 9:20 am EDT August 3, 2007...
  2. Greg Bernhardt

    35W bridge in minneapolis collapses

    "A bridge over the Mississippi River in Minnesota has collapsed, sending cars into the water, The Associated Press reports" - CNN. Hope everyone here is ok! My sister and brother-in-law take it every day, but they phoned us ok.
  3. P

    Understanding Bridge Rectifiers: A Guide to AC Theory and Function

    http://www.play-hookey.com/ac_theory/images/rectifier_bridge.gif When I see this, I remember that my teacher never explained this clearlly to me. As I see it (follow the Blue Current), when the current returns to the negative (temperorary) terminal, there can be 2 possible paths. It can take...
  4. M

    Exploring the Horizontal Displacement of a Rock Kicked Off a 321m High Bridge

    A bridge rises 321m above the Arkansas river. Suppose you kick a rock horizontally off the bridge. The magnitude of the rock's horizontal displacement is 45.0 m. Fine the speed at which the rock was kicked. (This is not what i ask you here) Does the ball travel 321m vertically in free fall...
  5. C

    Make a Bridge Rectifier Circuit: Tips & Suggestions

    I want to make a bridge rectifier circuit to give me 6v or 9v DC power from 220v 50-60 Hz AC supply. I know the circuit, but don't know which diodes and capacitors to buy for it. This would be the first time I'm doing something like this, so any suggestions/tips would be appreciated.
  6. H

    Circular Motion of Car in Vertical Bridge

    1. A car of mass 1500kg moving at constant speed of 80km/hr passes over a humpback of a bridge of radius of curvature r. The car remains in contact wit the road as it passes over the top. a) Express N, net force exerted by the car on the road, in terms of r. b) Determine the minimum...
  7. Z

    A Full Wave Rectifier Bridge With A Capacitor

    1. i have a transformor 12 v rms i want to do a full wave rectifier bridge with a capacitor and get a 12v dc 2. i need to know how i can calculat the capacitor needed and the resistor and wat to know how many voltage should the capacitor be (NB: i don't know wat is the current of the...
  8. T

    Simple bridge design analysis

    How do you resolve an angled member supporting a vertical load into a column and cantalivered beam problem?
  9. C

    How Much Force Do Pillars Exert with a Parked Car on a Bridge?

    Homework Statement A uniform bridge 20 m long and weighing 4.00x10^5N is supported by two pillars located 3 m from each end. If a 1.96x10^4 N car is parked 8 m from one end of the brige, how much force does each pillar exert? Homework Equations (Fgb*L/2+Fgp*d)/L(sin theta). The...
  10. turbo

    Felt a mild tremor on a bridge

    About 1:20 this afternoon, I was standing on a very sturdy rigid steel walking bridge spanning the Kennebec River in Skowhegan. I was bracing my forearms against the railing and taking a picture of the river valley downstream, when suddenly the bridge shuddered for a few seconds. I looked up...
  11. M

    Exploring My Arch Design Bridge: Physics of Spaghetti Structures

    I'm currently in my final year of high school, doing physics. We have been given an assingment about bridge structures. Basically, we build a bridge out of spaghetti, test it and discuss it. I'm thinking of things in which I can talk about. I've built an Arch Design Bridge. Mainly due to...
  12. A

    Truss and Suspension bridge.

    How will I calculate the forces involved in a truss and suspension bridge, my teacher did not explain this fully and I'm confused as hell.
  13. S

    Bridge Rectifier for Thrige Titan 10 HP Motor

    Could anyone suggest what size and best type of bridge rectifier to use with this motor,Thrige Titan 10 HP, 7.5 KW,240V DC- 36.3 Amp,Excitation 150/300 V- 1.4/0.7 A. Also would I be able to run this motor off my house current of 240 V, This motor will be used to power a winch for pulling logs...
  14. K

    How Is Voltage Across a Capacitor Determined in a Bridge Circuit?

    A Bridge Circuit Capacitor [Solved] EDIT: Problem has been solved. Homework Statement "The circuit has been connected as shown in the figure for a 'long' time. (See attached diagram) What is the magnitude of the electric potential across the capacitor? Answer in units of V."...
  15. G

    What is causing my full-wave bridge circuit to only produce a half-wave output?

    I am constructing a full-wave bridge with the following: - four D1N4148 - Function generator (50Hz with 10 Vpp) - 1k ohm resistor - Oscilloscope I've been trying to construct the circuit, but every time I did it I always get a half-wave instead of a full-wave. All the diodes are working...
  16. M

    Bridge design homework problem

    I need a bit of help here. I have an upcoming assessment towards bridge design. The task is to create and construct a bridge made out of dried spaghetti sticks. The bridge is to be as light as possible while holding the most weight. I currently have 1 main design I'm leaning towards, but I'm...
  17. Q

    Deriving a balanced bridge equation

    I am having trouble finishing this problem. I am supposed to first derive an equation for V_5 in this circuit: http://img292.imageshack.us/img292/599/picture3qy2.png I applied a Delta-Wye transformation to get here: http://img292.imageshack.us/img292/9672/workot8.jpg From there I am...
  18. F

    Building a Newspaper Bridge - Physics Homework

    Homework Statement In physics class, we are now starting to build free standing newspaper bridges. We are allowed to use only newspaper and glue, but we can use as much of those as possible, as long as it meets the following conditions: 1. It must be less than 254 g (don't ask me why)...
  19. K

    Calculating Force at Left Point of Support on Bridge

    Homework Statement A bridge of length 60 m and mass 51800 kg is supported at each end. A truck of mass 45000 kg is located 26 m from the left end. Homework Equations What is the force on the bridge at the left point of support? The Attempt at a Solution I know your supposed to...
  20. R

    Help with an h bridge controller

    i'm using p type mosfets for an r/c cars h bridge controller (the two n types have been replaced with p types because of their lower internal resistance) and was wondering if there is a way to do it without voltage pump circuits that stills alllows a P.W.M. torque controller.
  21. W

    Copper Wire as a Salt Bridge: The Mystery of its Function in Voltaic Cells

    in a recent chemistry experiment at school, two voltaic (galvanic) cells were set up with the same solutions in either beaker (one being Copper Sulfate, and the other was another metal solution) anyway, one had a potassium nitrate salt bridge, the other a copper wire salt bridge... sooooooooooo...
  22. S

    Build Paper Bridge: Guidelines & Suggestions

    I just got this project for my physics class. I need to build a paper bridge out of only paper and Elmer's glue. The bridge must be free standing with the highest point on the bridge being the roadbed (i was thinking i could do a suspension bridge, but I can't under that guideline). The...
  23. P

    Establish wheatstone bridge priciple by using kircchof's law

    How i can Establish wheatstone bridge principle by using kircchof's law?please tell me in details or send pdf or .doc files to:pavelavw@yahoo.com
  24. A

    Anderson bridge used to measure self-inductance.

    how does it work?? i am really too confused and can't understand its idea. can anyone help??:confused: :confused:
  25. K

    1d Kinematics, bridge jumping.

    Bond is standing on a bridge, 10 m above the road below, and his pursuers are getting too close for comfort. He spots an approaching flatbed truck loaded with mattresses and decides to jump from the bridge onto the truck to make his getaway. He notes that the telephone poles the truck is passing...
  26. L

    Bridge in the Context of A Spring.

    We have weekly problem sets that lead us through a "story" of sorts. In this week's, a group of tourists are on a newly-built, albeit poorly-designed bridge. The question reads: "The tourists bend their knees and, at the count of three, jump upward simultaneously. While their feet are in...
  27. C

    Engineering Theveninizing a Wheatstone Bridge Circuit

    I'm working on a problem that has me confused. Perhaps someone might know of a resource with examples of different Wheatstone bridge circuits both balanced and unbalanced that use Thevenin's Theorem by eliminating different resistors from the bridge. The bridge I'm working with has one DC...
  28. J

    Is Precision of Excitation Voltage Important for Load Cell Accuracy?

    Hello, I'm trying to decide how I will provide excitation voltage to the wheatstone bridge of a load cell. The output of the load cell will be amplified by an LT1167 In-Amp. How concerned should I be about the precision/accuracy of the excitation voltage? Since the In-Amp will reject common...
  29. ZapperZ

    FINAL VOTE - Bridge Over Troubled Water

    This promises to be a rather difficult final round of voting. Good luck to everyone! 1. hypatia 2. Kurdt http://img329.imageshack.us/img329/219/tyne270904026ut8.jpg 3. hypnagogue http://img106.imageshack.us/img106/2142/bbridgeap8.jpg 4. turbo-1...
  30. ZapperZ

    VOTE Group 2 - Bridge Over Troubled Water

    The second group of pictures for this contest. 1. SpaceElf http://img63.imageshack.us/img63/1809/bridge1fx6.jpg 2. turbo-1 http://img204.imageshack.us/img204/8899/wirebridgeos4.jpg 3. FredGarvin http://img247.imageshack.us/img247/1117/brindge004smbe4.jpg 4. ZapperZ 5...
  31. S

    Particle statics - A bridge span

    Heres the problem. A bridge span is 5m high and 20m long. Find the verticle force and the horizontal thrust on each of the piers P in terms of weight suspended from the center of the span. I really hope you can understand the geometry of the problem without the drawing(there was a drawing...
  32. ZapperZ

    Photo Contest - Bridge Over Troubled Water (8/16-8/22)

    Bridge Over Troubled Water This week's theme is all about bridges! It can be anything from the covered Bridges of Madison Country, to the hilarious Tacoma Narrows bridge. A bridge (or bridges) must be the main focus of your picture. Contest Rules: 1. Any digital photo or...
  33. Astronuc

    You can blow up a bridge - legally

    From NPR -http://www.npr.org/templates/story/story.php?storyId=5637737 To enter the contest to blow up the Woodrow Wilson Bridge - http://www.wilsonbridge.com/toughestcommute/index.html
  34. J

    Build a Strong Bridge with Limited Resources: A Budget-Friendly Challenge

    Here's a little challenge: You need to build a bridge to fill a 40-cm gap. The bridge must be able to support 1kg for 10 seconds and flex no more than 2.5 cm. Your budget is $95 million. Materials given are 18-cm straws at $1m, 18-cm toothpicks at 18-cm each at $5m, 6-cm toothpicks at $20m...
  35. C

    Improve Bridge Design for Heavier Loads

    Bridge Design... I have a design exam on friday and I need some tips on revising for a particular question. We designed a bridge from aluminium angle and strip and tested it under a load to see what it could withstand before failure. I have been told by my lecturer that the question will ask...
  36. R

    Max amount of different bridge distributions?

    I was wondering about this when playing bridge with my friends. I understand, that one player can be dealt C^{13}_{52} different distributions of the cards. But how to calculate the probability, that all players will get the same cards?
  37. Schrodinger's Dog

    It is illegal to drive a pig over London bridge

    It is illegal to drive a pig over London bridge and it is also illegal to set off a nuclear weapon in the city limits of LA.It is perfectly legal to shoot someone from Wales with a crossbow should they be found in the county of shropshire on the weekend. I'm generally pretty law abiding and I...
  38. P

    Overweight Truck Crossing a Bridge

    A truck carrying chickens is too heavy for a bridge that it needs to cross. The empty truck is within the weight limits; with the chickens it is overweight. It is suggested that if one could get the chickens to fly around in the truck by banging on the truck side, it would be safe to cross the...
  39. M

    Make a bridge out of popsicle sticks homework

    Hey all, I've got a project that I have to do. I have to make a bridge out of popsicle sticks. However, it's a competition and only the winner receives full credit. The bridge with the highest ratio of weight held to bridge weight wins. Weight Held (Pounds) ------------------------- =...
  40. U

    Understanding the Tacoma Bridge Collapse: Causes and Differences in Resonance

    i remember in high school my physics teacher used the example of tacoma bridge to teach us resonance. what exactly is it that caused tacoma to collapse? how is forced resonanace different from normal resonance?
  41. K

    How high is the bridge above the water?

    No 16 page 96: How long does it take for a car accelerating at 3.5 m/s^2 to go from rest to 120 km/h . Hint: first, change the velocity from km/h to m/s. No. 17 pag. 105: A rock is dropped from a bridge to the water below. It takes 2.4s to hit the water. find: a) the...
  42. E

    Juggling Across a Bridge: Will It Work?

    Please tell me if my reasoning is correct. a juggler carrying three balls wants to walk across a bridge that can only support the weight of the juggler and two balls. in order to make one trip, the juggler decides to juggle the three balls while walking across the bridge. that way, the...
  43. C

    Damped and Driven Oscillation of a Bridge

    Sorry that I had to use an image file, I was having a lot of trouble using the Latex system. http://www.flamingice.5gigs.com/Question.gif Ok... We know the amplitude of the oscillations, and the force per person, so all we need to do is find Fmax, by finding other values and substituting...
  44. P

    Bridge Force Calculations for Hiker's Weight

    A hiker, who weighs 696 N, is strolling through the woods and crosses a small horizontal bridge. The bridge is uniform, weighs 4440 N, and rests on two concrete supports, one on each end. He stops 1/4 of the way along the bridge. What is the magnitude of the force that a concrete support exerts...
  45. E

    Equilibrium Question on Bridge

    Question Sir Lancelot rides slowly out of the castle at Camelot and onto the 12.0-m-long drawbridge that passes over the moat. Unbeknownst to him, his enemies have partially severed the vertical cable holding up the front end of the bridge so that it will break under a tension of 5.80 \times...
  46. H

    I would like to know the mechanism of LCR bridge

    Who can tell me the theory about the LCR bridge to measure capacitance?
  47. L

    Build a Spaghetti Bridge - Holds 10-15kgs!

    hey, the rules are as follows: 70cm long 200g heavy use anything to keep it together my preference: holds about 10-15 kgs (it can be done) spaghetti doesn't stretch or bend, cause it snaps, my dad thought of tube spaghetti (bucatini), one in the centre, and five round the outside...
  48. L

    Building a Spaghetti Bridge - Tips & Ideas

    hey, the rules are as follows: 70cm long 200g heavy use anything to keep it together my preference: holds about 10-15 kgs (it can be done) spaghetti doesn't stretch or bend, cause it snaps, my dad thought of tube spaghetti (bucatini), one in the centre, and five round the outside...
  49. Ivan Seeking

    The Amazing Spider Web: A Fifteen Foot Long Suspension Bridge

    Lately I have seen a number of spider webs [really, it looks like a single strand] running horizontally from one tree to the next. This morning I saw one over fifteen feet long, nearly perfectly level, and suspended abouty eight feet above the ground. How does a spider span the fifteen feet from...
  50. Andre

    Solve Bridge Puzzle: South Makes 6 NT

    Can I amuse anybody with a bridge puzzle? I made it some 25 years ago and it took almost a year to debug it. So if you find the solution within minutes then that’s either brilliant or you found one of the two build-in traps. The real solution looks unusual. South plays six No Trump, west...
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