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. G

    How to bridge the gap from a Thomas or Stewart calculus book to this?

    In my other thread on choosing a precalculus book for review, I went off topic and into calculus books, and how there seem to be these 3 main categories of books universities and high schools use -> the 1000+page ones with tons of examples, very computational, new editions every other year, etc...
  2. Govind_Balaji

    Velocity of train if it passes 2km bridge in 110sec and a point in 10s

    Homework Statement A train passes through an electric post in 10 seconds. With same velocity, it passes through a 2km long bridge in 110 seconds.Find the velocity of the train: a)18kmph b)36kmph c)72kmph d)90kmph. Homework Equations The Attempt at a Solution...
  3. S

    Calculation of absolute electrode potential and salt bridge qns

    >According to http://www.chemguide.co.uk/physical/redoxeqia/introduction.html each electrode has an absolute electrode potential which is the difference between the positiveness and negativeness. So if we had a Zn plate in water and it has a negative charge of -5 on the metal. Would the absolute...
  4. D

    Miniature Bridge Design Ideas: Simple or Complex?

    So I am the leader of a small group who has to build a bridge in 30 minutes on the last day of school. The only materials we can use are play-dough, straws, and rubber bands and it has to stretch 30 cm between two tables. Though I was looking for some ideas of a bridge design to use. Should I go...
  5. T

    How can I set a frequency in a Wien bridge oscillator

    Hi all, Im new here :-) So I am designing a simple Wien bridge oscillator, and need it to be set to a specific frequency. This is my circuit: Where C1 = C and C2 = C and R3 = R and R4 = R Im using ω=1/(C2R2) where C = my capacitor values and R = my Resistor values. My problem is, however...
  6. H

    Einsteins-Rosen bridge different from schwarzschild black hole metric?

    Hello, if you could help, I will be glad. I am studying the Einsteins-Rosen bridge (a matematically solution of the black hole) and I thought that the Einsteins-Rosen bridge was what we found making the Schwarzschild metric a change in kruskal coordinates. But reading an scientific article it...
  7. A

    High ouput power voltage using half bridge resonant

    Hi Im doing a project based on half bridge converter of IR2153 which could produce a high output voltage using the LTspice simulation by means of half bridge topology. Well, I am just wondering as the volatge across the two capacitors that is pointed in the image shown wasnt give half the...
  8. K

    Wheastone Bridge Homework: Compute i1 and i2

    Homework Statement Compute i1 and i2 in Figure a). R3 = R4 = 6Ω, and R5 = R6 = 12Ω. Homework Equations KVL and KCL The Attempt at a Solution Since R3 / R5 = R4 / R6 , it's a Wheastone Bridge and i2 = 0, and i1 = \frac{20}{9} A. But my question is, why circuit in Figure b) is not...
  9. L

    Calculating Car Mass with Constant Speed on a Bridge

    If a car is traveling towards a bridge at a constant speed of 20ms-1. The bridge takes 30s to cross entirely. The car creates a force of 3000N. Calculate the mass of the car when it is on the bridge. a=(v2-v1)/t F=ma I figured that a = 0 due to the fact that the car is traveling at...
  10. I

    How Do I Design a Half H Bridge for My Robot Wars Project?

    Im a second year mechanical engineer at university, we have a group project to design a robot for robot wars. To do this we have to design something called a half H bridge. I have very little understanding of electrical engineering and our electrical engineer has dropped out of uni leaving us to...
  11. B

    Does the back bridge really fix back problems?

    It claims to be able to fix problems such as slip discs, scoliosis and lordosis, setting the spine back into a normal position by simply lying down on the curved surface and letting it stretch the spine. Is this really true? Source: http://www.backbridge.com/
  12. K

    2D Kinematics - 2 rocks off a bridge

    2D Kinematics -- 2 rocks off a bridge Homework Statement Heather and Jerry are standing on a bridge 60m above a river. Heather throws a rock straight down with a speed of 14m/s . Jerry, at exactly the same instant of time, throws a rock straight up with the same speed. Ignore air...
  13. M

    Single-phase hybrid bridge rectifier

    Hello, I need your help. I am not sure what formula to use for this question. Do you think this is the right one? What's the influence of L/R on this circuit?
  14. AbhiFromXtraZ

    Resistance Of A Unbalanced Wheatstone Bridge Circuit

    Resistance Of An Unbalanced Wheatstone Bridge Circuit How to find the equivalent resistance across the battery (I mean the whole circuit) of a Wheatstone Bridge circuit IF GALVANOMETER CURRENT IS NOT ZERO (i.e. unbalanced circuit)?
  15. N

    Trying to use an old router as a wireless bridge

    I recently rearranged my house, and now the most convenient place to set up my computer is unfortunately inconvenient to run a wire to. Fortunately, I have an old router lying around (Linksys E2500), that I figured I could use as a bridge, and while it wouldn't be as fast as connecting a wire...
  16. D

    Engineering What happened to i3 which joins with I1 to become I4?

    http://i42.tinypic.com/10sfxa1.jpg Im having trouble with the bridge circuit. I see the current has been given 2A So 6.6=3i1+2(i1-i2) 5i1-2i2=6.6 So applying KVL I get 0=4i2+5i1-3(2-i1) 8i2+5i1=6 So using simultaneous equations I get- 5i1-2i2=6.6 5i1+8i2=6 So 10i2=12.6 i2=...
  17. EagleOnePro

    What are some options for H-bridge ICs to power 12V 3.6A loads?

    Hi, I am in the market for an H-bridge IC to power 12V 3.6A through. This is the circuit. http://fritzing.org/projects/drive-motor-using-l293d-sn754410 Do you know where I could get an H-bridge like the one in the diagram? so I can power a bigger load and use 12V 3.6A...
  18. P

    Advanced Project - Wheatstone Bridge for TCR measurements

    Advanced Project -- Wheatstone Bridge for TCR measurements Ok, so I have to do this experiment on my own as part of my coursework this year and I picked something called the temperature coefficient of resistance. I think I basically have to determine the TCR or copper and I'm almost...
  19. L

    Arch Bridge Compression Calculations - Help

    Hi all, basically we're building a model bridge (30 grams) for a mechanical engineering project out of balsa wood and kevlar (for the strings). I've attatched a pdf file of the bridge design, although it doesn't show the strings. We are wanting to do some basic load compression calculations...
  20. F

    Crossing Weak Bridges - Driving Fast or Slow?

    If you need to cross a bridge and you have reason to worry about its load-bearing capacity, do you choose to drive across it fast, or slow, or does it not matter? What are the considerations?
  21. B

    Electronics, Wheatstone bridge, with a twist.

    Homework Statement The bridge circuit below is used to monitor temperature using a thermometer. The thermometer RT has resistance of 100 Ω at 0°C and a linear coefficient with temperature of 0.005 Ω/°C. What is the sensitivity of the bridge (ΔVOUT/ΔT) around 100 °C for ΔT = 1°C? How does it...
  22. D

    Differential Equation for a Wien Bridge Oscillator

    I am trying to write out a differential equation for the Wien bridge oscillator circuit. I have attached a picture of the circuit. I am considering ideal conditions. I am trying to solve for the output voltage but I need help setting up the differential equation.
  23. T

    Can AC Excitation Remove Offset Error in a Wheatstone Bridge Torque Meter?

    I have a torque meter using a full-bridge Wheatstone bridge (all legs are strain gauges). The bridge has some non-zero, unknown offset (it's old). I would like to strip this offset out prior to signal amplification. My theory is, under DC conditions, the offset exists, which mucks up the...
  24. S

    Understanding Flyback Diode Utilization in L293 H Bridge IC

    So in an application like this: The coil of the motor will, by Lenz's Law, induce a very large negative voltage across its terminals. Would this voltage be very negative at the left terminal of the inductor and very positive at the right? In this way the diode will conduct, but the negative...
  25. S

    Understanding Half Bridge Driver

    I'm trying to understand what this IC is doing and what the "typical application" circuit is doing http://www.onsemi.com/pub_link/Collateral/NCP1392-D.PDF It looks to me like this is the basic idea. AC comes in, PFC is done, signal is rectified so that a DC signal is coming into the IC...
  26. Tesladude

    Maximizing Power Output: Amplifiers in Bridge Mode

    I read that bridge mode in amplifiers will, for example, take a 100 watt amplifier at 8ohms and turn it to a 200 watt amplifier at 4ohms. I was going to use 2 tda2050 amps, each running one speaker, but if I use 2 amps in bridge running 2 8ohm speakers in parallel, would this give me double...
  27. P

    Choosing Bridge Rectifiers: Can One Type Handle Both AC and DC?

    bridge rectifier design... Can I use the same bridge rectifier for AC as well for DC voltages? My AC mains is regular 265Vac and DC is 40Vdc. How should I choose bridge rectifier? (In other words, what are the parameters I need to check while selecting diodes for bridge rectifier?) Thank...
  28. R

    Wheatstone bridge arrangement with an ideal wire in middle

    Homework Statement I came across this questions in one of the online entrance tests,so i do not remember the exact values,I remembered the arrangement. ________________ |... |...| |... A...C 2v...|--------| (Please ignore the dots,they are to prevent...
  29. George Jones

    News Bridge collapses in Washington state

    http://usnews.nbcnews.com/_news/2013/05/23/18456081-bridge-collapses-in-washington-state-cars-people-in-water?lite
  30. T

    Help with plastic bridge design

    I am in a high school Precalculus class. We are about to have a project where we build bridges with PVC and twine. The goal is to hold as much weight as possible. For this project, I believe we will be given 28 feet of PVC, a roll of twine, and 5 or 6 days to design and construct our...
  31. mathmaniac1

    MHB Efficient Family Bridge Crossing Strategy

    5 members of a family are to cross the bridge and the bridge can hold only 2 at a time.Its also dark so they have a lamp...They have to do the crossing in less than 30 seconds... It takes 1 second for the boy to cross the bridge,3 seconds for his fatty brother,6 seconds for their father,8...
  32. K

    Calculating the maximum bending moment on a bridge

    Homework Statement Calculate the maximum bending moment on the bridge section using the values given. (REFER TO DIAGRAM ATTACHED) mass of bridge = 9250 kg mass of car = 2250 kg length of bridge section = 26 m Homework Equations I worked out previously that: Reaction at A = reaction at B =...
  33. A

    Which design is better for a popsicle stick bridge: left or right?

    Homework Statement i am building a popsicle stick bridge, and i basically have two trusses, which i am attaching together to make the bridge (each are one side of the bridge), and I am having trouble deciding which way to orient the two trusses. if you look at the picture below, you can...
  34. S

    Grid connected transistor bridge inverter

    Homework Statement Hi there. I was just wondering if anyone can conform that my method for this problem is correct so far? The transistor-bridge converter shown below is being used to connect a PV array to the grid. For the purpose of this coursework, you may assume that: • The PV array...
  35. S

    How to connect strain gauge in the form of wheatstone bridge

    HAI I am SYED , i am doing my project using strain gauges. Problem description: I have 4 strain gauges bonded to an octagonal ring. The strain gauge i am using is METAL FOIL TYPE , GF(gauge factor) -2 and 320ohm resistance. The strain gauge has two terminals ,my question is (1) Can anyone...
  36. N

    Finding Forces in a 2D Bridge: Determining Pressure and Tension

    Homework Statement We have this bridge, which is 2D - as shown picture. How I determine which sticks are subjected to pressure and which tension? How big are these forces? Sticks are intangible, mass of car is M. From the picture, we can determine the length of the sticks. Picture...
  37. N

    Mass on Bridge, Find Force of Friction when bridge is barely inclined

    Look at the picture attached. There is a mass on a drawbridge, which is inclined at half a meter. We have the Normal force, the coefficient of static friction, force of gravity and the force of friction pushing the mass upwards to the end of the draw bridge that is most inclined. We also have...
  38. K

    Exploring Einstein-Rosen Bridges: Theoretical & Astronomical Possibilities

    Do physicists know what causes an Einstein-Rosen bridge (a wormhole) to open up? Does astronomy know of any stable wormholes within the known universe? In theory, can wormholes be artificially created? And could we use these cosmic gates to send spacecraft to distant parts of the universe and...
  39. C

    Wheatstone Bridge with Thevenin's Theorem

    Homework Statement http://imageshack.us/a/img685/602/homeworkprobsg29.jpg The bridge circuit provides a good illustration of the use of Thevenin's theorem. Find the current through the bridge resistor (50Ω). Homework Equations V = IR source transformations, current division, voltage...
  40. N

    Exploring the Mysterious Boat Under the Bridge

    When I went today after the bridge over the river, I thought... It's about how I see the situation. I noticed that just below me (under the bridge) was situated bow boat, sailing directly under the bridge. For how long, the boat will be on second side? How will the solution be different if I go...
  41. haruspex

    Ranking the pairs in a bridge match - what precision?

    I've come across a bug in a program that calculates rankings from the results of a bridge tournament. It should be fixable by increasing the precision, but it's not obvious what the precision needs to be. (I don't have access to the source and anticipate push back from the coder, so I need it...
  42. T

    Brownian bridge and first hitting times

    Hi, Letting W be a standard brownian motion, we define the first hitting times T_{a}=inf\{t:W(t)=a\} with a<0 and T_{b}=inf\{t:W(t)=b\} with b>0 The probability of one hitting time being before an other is : P\{T_{a}<T_{b}\}=\frac{b}{b-a} I'm looking for this probability in the case...
  43. Spinnor

    Criticism of small bridge design welcome.

    Criticism of small "bridge" design welcome. I live near a park that has two large hiking areas divided by a stream. If those areas were linked by a bridge the number of possible hikes that could be taken would be increased. The stream at one "crossing" is about 30 feet wide and normally has a...
  44. C

    Stargazing Zhumell Z12 vs Meade Light Bridge 10

    Hey guys! I am interested in buying another telescope and was wondering if any of you had any advice about either of the two I'm split between. It seems to simply come down to a quality? vs aperture argument. The first scope is a Zhumell Z12 with a 12 inch aperture seen here...
  45. J

    Thevenin equivalent for wheatstone bridge

    Hi, can anyone help me on how to find Thevenin equivalent resistances for a Wheatstone bridge configuration? I've searched all over google and youtube, but I haven't been able to fully understand the procedures.
  46. Femme_physics

    Yet another Wheatstone bridge with thermistor

    Homework Statement So I got a thermistor here and am told that in the range 0-80 celsius the thermistor's resistance is given by Rt = R0 - kT ...whereas R0 = 100 ohms which is the thermistor resistance at 0 celsius. k = 0.5 kohms/celsius. T is of course temperature. The op-amps are ideal and...
  47. Femme_physics

    Thermistor in Wheatstone's bridge

    I'm told to presume that R1=R2=R3 http://img716.imageshack.us/img716/7610/thermistor.jpg And I have a chart for the value of the thermistor based on the temperature. At 20 degrees the thermistor is 2814 ohms My question is since they told me that R1=R2=R3, does it necessarily mean that...
  48. N

    Choosing materials for a bridge

    Hello everybody, We need your advice with a project for building a simple one-beam bridge. We have figured out the dimensions, required load, max allowable stress and safety factor. We need to choose a material that would support our requirements. Which formula should we use to compare...
  49. D

    Resolving forces in 7 member bridge help

    http://imageshack.us/photo/my-images/853/bridgel.png/ I don't answers course just some guidance. I need to find the forces at each joint, and stresses inbetween too. I've calculated the reaction forces by taking moments as 779N at far left and 692.5N at far right. Now I'm using trig of...
  50. H

    Resonance in action: Russian Bridge

    Somebody slept through their lecture on resonance. I don't know how to link video. http://www.youtube.com/watch?v=WEQrt_w7gN4&feature=related https://www.youtube.com/watch?v=http://www.youtube.com/watch?v=WEQrt_w7gN4&feature=related
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