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

    Failure of the Tacoma Narrows Bridge

    i am, thus, attempting to understand the physics of the collapse of the Tacoma Narrows. can please explain what i have found to be the cause of the final distruction: single-degree-of-freedom torsional flutter? or if you know anything else about this event, please explain!
  2. Shahil

    How do flyback diodes protect FETs in switching power supply circuits?

    Help! Full Wave Bridge AGAIN! https://www.physicsforums.com/showthread.php?t=66883 I posted this in the Homework help zone and nobody helped me :cry: Please can someone here help me! I would appreciate it! Thanks!
  3. Shahil

    Unlocking the Mystery: Calculating Values for a Full Wave Bridge Circuit

    Help! Full Wave Bridge! Hi guys! Okay - I know that this is a straight-forward intermediate level circuit theory problem but uh...I've forgotten how to do it so I need help! :confused: :confused: :confused: :confused: :confused: I have a full-wave rectifying bridge connected to a...
  4. I

    Good Bridge Design for Balsa Wood & Steel Blocks

    For our balsa wood bridge, 1/8 in square, would a bridge that crosses catilever and arch styles together work well? The steel blocks attached to the test table are acting like abutments, so all of our forces can be directed to them, right?
  5. I

    Build a Balsa Wood Bridge: Explaining Arches & Compressive Strength

    Can anyone or does anyone know where I can get a good explanation of how to figure out how big an arch should be for a bridge? I am thinking of making one for our competition, and if I can't get that to work right, I will switch to a king post deisgn. Oh, and is it true balsa and other...
  6. L

    Tacoma Bridge Collapse: Physics of Vibration and Sound

    I changed my mind, I'm not fickle, th stethescope was all i could remember... Anyway, apparently the tacoma bridge collapse was due to the bridge 'vibrating', and obviously the supports couldn't hold it... If you know anything about how the sound part of physics fits into this your help...
  7. H

    Calculating Resonant Frequency of a Bridge with Added Support

    I am having trouble with the following question: A bridge has a natural frequence of 10 Hz. If a support is placed one-third of the way along the bridge, what is the new resonant frequency? How should I start this problem?
  8. J

    Calculating Bridge Pillar Forces: Solving a Seesaw Problem

    the problem reads: a uniform bridge 20 m long and weighing 400,000 N is supported by two pillars located 3 m from each end. if a 19,600 N car is parked 8 m from one end of the bridge, hoe much force does each pilliar exert? i was thinking about using something like (W1)(d1) = (W2)(d2) that...
  9. Z

    Need help:How to measure stress on a bridge.

    I am doing a science project which i have to measure the stress put on the models of 3 different kinds of bridge, and was wondering what the most efficient way to measure the force per square area. Thanks.
  10. M

    Build a Newspaper Bridge | Physics Lab Tips

    I'm eventually going to have to build a bridge in Physics class, made of newspaper, for one of my labs. It's supposed to be a free-standing bridge that can hold a 3 or more kg load, while spanning a 1 meter gap. I'm allowed 10 sheets of newspaper and 1 meter of tape. Does anyone have any...
  11. N

    Bridge Building with Pasta Assignment

    Hey, my physics teacher handed us this assigment and said have fun. He didn't explain what to do or go over how bridges work. So I was wondering if anyone here has done something similar to this. I believe I can work out the design, but what kind of pasta and glue would be most appropiate to get...
  12. I

    Maximizing Bridge Capacity: A Weight Distribution Dilemma

    My first post... So be nice, or I'll blast you with a phaser... o:) You are at one side of a canyon at the start of a bridge. The only way to cross the canyon is over the bridge. (no tricks to this, just a normal crossing of the bridge, don't try to walk on water here) On you side are 3...
  13. N

    Understanding Wheatstone Bridge Circuit: How to Solve for Unknown Voltages

    How do i solve this? I wasn't given any examples at all. But I've tried to do this. Iab + Iad = Ibc + Idc <--------- they have to or else Kirchoff's law violated. so Vab = Vad but I'm not sure if Vbc = Vdc? i'll continue assuming Vbc = Vdc Vab/40 + Vad/20 = Vbc/70 + Vdc/50...
  14. C

    Man & Woman Separating at 10 sec: A Bridge View

    a women is walking at a rate of 6 ft/sec across a bridge 40 ft above the water, a man in a boat is immediately below the woman on the bridge , at right angles to the bridge and at the rate of 4 ft /sec. how fast is the man and woman seprating at the end of 10 seconds what i have figured out...
  15. Y

    Steel bridge - increase dimensions by 5

    If you increase the dimensions of a bridge by 5, how much is its strength increases? How much is its weight increased? Any help is appreciated. Thanks
  16. R

    Need help on designs of Fettucini Bridge, by Thursday

    Hi! I'm currently doing a Fettucini Bridge project... The material allowed: 20 Fettucini 1 meter of masking tape Purpose: to hold more then 3 kilograms Please Help me~~~~ I need the replies by Thursdays. Thanks to anyone who takes time to read this message. Actual pictures are...
  17. A

    Creating a Strong Straw Bridge: Tips and Guidelines for a Physics Class Project

    Hi everyone, I've got to build a bridge from straws and pins for a year 12 physics class. Our bridges will be tested for strength by hanging weights off the bottom of them, and the strongest bridge wins. If the bridge collapses or the masses touch the ground, we fail. Here's some more...
  18. D

    How do you build & design a bridge with these materials?

    how do you build & design a bridge with these materials? 4 drinking straws 10 pieces dressmaker's oin 5 pieces of 5-peso coins (the bridge should be able to withstand the weight of these coins) 1 short bond paper and a 1 meter sticky tape Anyone who has performed this project...
  19. D

    How do you design a bridge with these materials?

    how do you build & design a bridge with these materials? 4 drinking straws 10 pieces dressmaker's oin 5 pieces of 5-peso coins (the bridge should be able to withstand the weight of these coins) 1 short bond paper and a 1 meter sticky tape Anyone who has performed this project...
  20. M

    Calculating R0 to Equalize RAB and R in Bridge Circuit

    In the circuit shown http://www.his.com/~mhtesler/BridgeConfiguration.jpg , what value of R0 will result in RAB being equal to R?
  21. A

    Wireless USB type bridge thing?

    Hey guys; Is there currently any type of Wireless USB bridge thing? What I mean.. I have a laptop, and when I use my digital camera I have to plug it in the back of my PC, which means I have to pull out the USB cable and bring it to my laptop, etc. Is there any way I can have the USB...
  22. zoobyshoe

    Full-Wave Bridge Rectifier With Capacitor Filter

    I am putting together a control circuit for a DC motor. This motor requires 110 volts DC. It must be variable speed. I happen to have a nice continuously variable transformer box that goes smoothly from 0 to 130 volts. This should take care of the speed variations. I hooked this up to a...
  23. D

    Can You Cross A Bridge With Three Gold Bars?

    could some kind person please clarify a long standing argument within my circle of friends.It goes like this .There is a bridge spanning a gorge that can take a maximum of 80 kilograms(sorry for those not used to kilos ), a person wieghing 78 kilos must transport three gold bars weighing one...
  24. M

    Can a Trailer Fit Under a Parabolic Arch Bridge?

    Problem 11. A hauing company needs to determine whether a large house trailer can be moved along a highway that passes under a bridge with an opening in the shape of a parabolic arch, 12m wide at the base and 6 m high in the center. If the trailer is 9m wide and 3.2 m tall(measured from the...
  25. J

    Bungee jump from a bridge, how to find h

    Hi guys, I'm new :smile: Now, I came here in search of help to a homework problem I have. I've tried to solve for around 40 minutes now, and can't get past solving for k. Here's the problem. The way I'm trying to solve is is by setting up two parts. One, I just solve for K in general...
  26. Ivan Seeking

    Near Disaster Averted: My $1000 Summer Saves the Bridge!

    We almost had a small disaster yesterday. Get this: Going by the book, using good numbers and a known technique for making such estimates, [I have played with this a lot] last night, in our creek that normally carries about 200 gallons per second in heavy flows, we had approximately 1800 gallons...
  27. H

    What was the perfect excuse for trying out suit symbols in TeX?

    I've been dying for an excuse to try out the suit symbols in TeX, and I just had a fun bridge hand that is the perfect excuse! Here's your hand: \begin{array}{l l} \clubsuit: & KJxx \\ \diamondsuit: & KQxx \\ \heartsuit: & \\ \spadesuit: & AKQxx \end{array} Your partner opens...
  28. K

    Math, science and bridge (+other games)

    Well, I want to know what kind of games (preferably card games and board games) do you like to play. I specify the card game, bridge because people around me always give me the impression that if they love math, probably they also love playing bridge. Do you find people interested in math love...
  29. Monique

    Donkey bridge to remember amino acids?

    lol, I hope that a donkey bridge is a used term in English? I'll explain it, just in case.. it is to make an associative link between things to be remembered. Is there any easy way to learn the structures of all the 20 aminoacids and whether they are polar/nonpolar/charged? It would be...
  30. W

    What is the key to solving an unbalanced Wheatstone bridge with a current value?

    We have been doing a lot of work with wheatstone bridges in class lately and our teacher gave us a problem to try and I'm totally lost. The diagram that we were given has a 40 volt battery hooked to a wheatstone bridge circuit. The positive power flows into two resistors, one is 9 kiloohms and...
  31. D

    Bridge Design: Structural Analysis Help

    Am seeking input/help with structual analysis on new bridge design. See: http://groups.msn.com/DavesBridgesandTowers for details Dave
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