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. S

    Bridge parabola word problem

    Homework Statement 1. It is a word problem I need done by tomorrow morning. so please help: A new bridge is being constructed. The space between the support needs to be 1050 feet; the height at the center of the arch needs to be 350 feet. An empty tanker needs a 280 foot clearance to pass...
  2. G

    Wheatstone bridge in Linear Algebra

    Homework Statement I remember in physics class that we saw this set up.The ratio of r1/r4=r2/r3 is the same. There is no use for the current to head through R5 if it's the same energy on both sides. Now in linear I have no idea how to use this. Homework Equations ? The Attempt at a...
  3. S

    Probability of bridge collapsing

    Homework Statement Dystopia county has three bridges. In the next year, the Elder bridge has a 17% chance of collapse, the Younger bridge has a 6% chance of collapse, and the Ancient bridge has a 24% chance of collapse. What is the probability that exactly one of these bridges will collapse...
  4. E

    Building a Paper Bridge: Connecting the Rings and Deck

    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...
  5. S

    How is the Wheatstone Bridge equation affected when VG is not zero?

    I need help! WHEATSTONE! Homework Statement http://en.wikipedia.org/wiki/Wheatstone_bridge My pic. is almost same as this one, but R2 on the pic. is Rx at mine, Rx at the pic is R4 at mine. Pleas draw it up and help me: Homework Equations VE(voltage at left) is 9 V. VG(voltage in...
  6. N

    Horizontal Distance Between Log & Bridge | Homework Statement

    Homework Statement A log is floating on swiftly moving water. A stone is dropped from rest from a 75-m high bridge and lands on the log as it passes under the bridge. If the log moves with a constant speed of 5.0 m/s, what is the horizontal distance between the log and the bridge when the...
  7. T

    Calculating the Probability of Getting 13 Points in a 13-Card Hand in Bridge

    hi everyone Problem: In (a simplified version of) bridge: each player is dealt 13 cards out of a full 52 card deck. Where an ace is worth 4 points; a king 3 points; a queen 2 points; and a jack 1 point. The rest of the cards (2-10) are worth 0 points. Question: what is the chance of...
  8. M

    How to Calculate Forces in Bridge Points?

    Homework Statement The problem statement: Bridge of length: 200m Construction can expand horizontally to allow thermic expansion Masses of beams: small in comparison to the car Mass of the car: 1360 kg. The answers: Na= 11,0 kN, Ne= 3,67 kN, Fab = Fde = 7,35 kN, Fac = Fce = 6,37 kN...
  9. N

    Analyzing Errors of a Wheatsone Bridge Experiment

    I have done the data processing for a Wheatsone bridge experiment. The data are: 79,66 79,30 136,70 126,60 188,08 173,40 204,00 196,00 243,90 237,40 260,96 257,40 111,34 93,90 240,00 240,00 341,20 344,10 380,92 398,10 164,00 144,00 241,20 218,80 288,00 280,00 293,40 266,50 424,56...
  10. L

    Troubleshooting Bridge Rectifier in LT Spice Simulation

    Homework Statement I am to build a linear power supply in four stages. However, at stage two, i have to add a bridge rectifier to the ouput of my transformer. My lecturer at university says i should get a graph that is a sine wave, with the negative values reflected into the positive x-axis...
  11. K

    Potenital Differnce between Salt Bridge and rxn

    Homework Statement A 0.100 M solution of sodium palmitate (C15H31COONa) is separated from a 0.200 M NaCl solution by a membrane barrier that is permeable to Na+ and Cl-, but not to palmitate ions. I need to calculate the concentrations of the ions on both sides of the barrier once...
  12. A

    Why Is My Resistive Bridge Calculation Resulting in Different Voltages?

    Homework Statement I was trying to apply the formula of bridge Homework Equations V_{o} = (\frac{1}{1+R4/R2})-(\frac{1}{1+R3/R1}) The Attempt at a Solution File is attached...Small numbers with resistor names are their values in ohms... the answer I get is 6v...Here it is 1.5 v...
  13. D

    Sir Lancelot Equilibrium Bridge Problem

    Homework Statement 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...
  14. K

    Solving a Wheatstone Bridge with 5 Resistors

    Homework Statement A Wheatstone Bridge with 5 resistors http://img529.imageshack.us/my.php?image=physicsproblemmo7.png Homework Equations Use Kirchoff's Law The Attempt at a Solution I know that I have to use Kirchoff's laws to find the current at each junction and then at the...
  15. A

    Calculating Forces in a Static Equilibrium Bridge System

    http://img150.imageshack.us/img150/5393/bridgeef8.png http://g.imageshack.us/img150/bridgeef8.png/1/ Sum(T_z) [pivot at L] = 2 F_r - 4 mg = 0 2 F_r = 4 mg F_r = 2 mg F_r = 2 * 120 * 10 F_r = 2400 Sum(F_y) = F_l + F_r - mg = 0 Sum(F_y) = F_l + 2400 - 1200 = 0 F_l = -1200 Answer...
  16. Astronuc

    Robotic Prius: Self-Driving Across SF-Oakland Bay Bridge

    Robotic Prius takes itself for a spin around SF http://news.cnet.com/8301-11386_3-10042320-76.html Smart cars - so people can eat, read or sleep on their way to work?!
  17. C

    Q: What is the Purpose of a Capacitance Bridge & How Does it Impact Output Q?

    What is the purpose of a capacitance bridge? let's say 4 capacitors are arranged ...../.|.\ .....c1..|..c2 ...____ /...0...\ _____ ...|...\...|.../...| ...|...c3..|..c4...| ...|...\..|../...| ...|......| ...|......| 0 indicates the voltmeter. if 0 indicates a potential of 0, we get...
  18. A

    Finding the tension in a cable of a bridge

    [b]1. Compute the cable tension at the midpoint, the quarterpoint and support for a 1600 foot span with a sag at the midpoint of 100 feet, when the cable is loaded with 10 kips/foot spread uniformly along a horizontal line. Midpoint Cable Tension=? a)3200 pounds b) 16000 pounds c) 32,000...
  19. S

    Full Wave Bridge Rectifier

    Sometimes in Full Wave Bridge Rectifier circuits a small value capacitor is placed in parallel to the RC block at the output, such as the circuit diagram in the attached jpg. C1 has a much greater value than C2, and the result value of the parallel capacitors is almost the same. Can anybody...
  20. M

    Build a Spaghetti Bridge for 11th Grade Physics

    I need to make a spaghetti bridge for 11th grade physics. I already have an idea, though I would appreciate your opinions. :smile: Dimensions: The top can be 110cm long, 50cm high, and have a 10 cm width. The bridge can extend off the bottom 10cm and have a total length of 100cm (you may...
  21. A

    Carey Foster Bridge: Galvanometer & Its Opposite Deflections

    why galvanometer gives opposite deflection on both of its ends in Carey Foster Bridge ?give me its full explanation and its reasons?
  22. A

    Bridge Building Homework - Help a Year 10 Student Win the Engineering Challenge!

    Homework Statement Hey guys! I am a year 10 student from Australia and our school is having an Engineering Challnege. One of the tasks is to build a 80cm bridge using only paddle pop sticks and PVA glue. To win, the bridge must hold the most weight but have least mass. It would be...
  23. M

    How does a Wein bridge oscillator work?

    hi guys I am new in this forum hope I am not lost.I am desperately asking for your help on how a wein bridge oscillator works by reffering to phase shift and attenuation of the wein bridge networkthe phase shift and amplification provided by the amplifier and the type of feedback produced.thank you
  24. J

    Quarter- bridge strain gauge circuit

    Could anybody help me please? :cry If I have quarter- bridge strain gauge circuit, where strain gauge will have its initial resistance and i will add another 3 resistors, 1 on the same side like strain gauge, and another 2 on the opposite side, so I will balance circuit and my voltmeter...
  25. M

    Bridge tester design (for competition)

    I have to design a bridge tester for a tech design class. In researching the design, I need to decide on which material to use, but there are so many factors in this one choice that it's near impossible to do it all alone. First off, I understand the idea behind the common bridge building...
  26. G

    Question about using a wheatstone bridge to measure changes in resistance

    Hi I need to measure the small changes in resistance of a strain gauge. I have read that a wheatstone bridge circuit is used to do this.. but I don't understand why I can't just use a milliammeter to measure the change in current through the strain gauge and then use R=V/I to find the new...
  27. I

    Wheatstone bridge/ strain gauge question

    Need to do an experiment where I masure the strain of wood due to changes in temperature. I believe I need to use 2 strain gauges, one to measure the strain and the other to act as a dummy to cancel out any affects that heating will have on the strain gauge. I also know that a wheatstone bridge...
  28. H

    Why Did Our Geophysical Group Use a L&N Bridge Instead of a Slide-Wire Bridge?

    My teacher gave us this problem to work on: Homework Statement Some years ago I worked with a geophysical group that was looking for water in the Yuma Arizona area. Boy what it hot! Because of the high temperatures in the summer, water was badly needed in large amounts to irrigate crops...
  29. N

    Design of Single-Phase Half/Full Bridge ResonantInverter

    Hello, I'm trying to learn how to design a single-phase half- and full-bridge resonant inverter. I have been reading few power electronics books to get the theory behind the inverters but I'm having trouble finding design equations. Most of the values for the inductors, capacitors are already...
  30. B

    What is the Wien bridge frequency proof and how do you solve it?

    [SOLVED] Wien Bridge Frequency Proof Homework Statement The ac bridge circuit shown is called a Wien bridge (also Wein bridge). Show that when the bridge is balanced, frequency is found by the Eqn attached.Homework Equations w=2*pi*f Using the number from each branch as a guide, the...
  31. M

    Wheatstone Bridge: AC Source Effects on Balancing Condition

    Homework Statement Will the balancing condition get modified in Wheatstone bridge if AC source is used instead of a battery ? Homework Equations The Attempt at a Solution
  32. R

    Kate's Bungee Jump: Calculating Distance Below Bridge

    Homework Statement Kate, a bungee jumper, wants to jump off the edge of a bridge that spans a river below. Kate has a mass m, and the surface of the bridge is a height h above the water. The bungee cord, which has length L when unstretched, will first straighten and then stretch as Kate falls...
  33. M

    Constructing a Toothpick Bridge: Tips and Techniques for Success

    http://homepage2.nifty.com/SUBAL/BCTOPE.htm These are the rules. I am using Titebond and Elmers Wood Glue. I need help on construction and making it stand erect.
  34. M

    I need to build a bridge out of toothpicks. MAJOR HELP NEEDED

    Homework Statement weight limit-100grams roadbed must span 500mm of gap must provide space for hook (15mm x 15mm) Must be only built of round toothpicks and glue. Anybody have a clue How to do this/ Homework Equations LUCK?? The Attempt at a Solution i FIGURED i would do a...
  35. M

    Minneapolis bridge collapse report

    The preliminary report is out on the bridge in Minneapolis that collapsed last year, The BBC claims they found that some of the gusset plates that failed were only half the thickness of the rest and are calling it a design error. Although they cannot find the original design so it's not clear...
  36. A

    Two objects are dropped from a bridge

    Homework Statement two objects are dropped from a bridge, an interval of 1sec apart during the time that both objects continue to fall their separation______ Homework Equations The Attempt at a Solution I thought it was stays the same but someone said it wasn't so my next guess...
  37. E

    Probabilities Involving Bridge

    Homework Statement (1) In a hand of bridge, find the probability that you have 5 spades and your partner has the remaining 8. (2) Compute the probability that a bridge hand is void in at least one suit. (3) Compute the probability that a hand of 13 cards contains: a. the ace and the...
  38. L

    How Wide Should Expansion Cracks Be Between Concrete Slabs to Prevent Buckling?

    Homework Statement A concrete highway is built of slabs 28 m long (20°C). How wide should the expansion cracks be (at 20°C) between the slabs to prevent buckling if the range of temperature is -30°C to +56°C? Homework Equations [delta]L = aL[delta]T The Attempt at a Solution I...
  39. B

    Testing Compression/Tension of Popsicle Sticks in Physics Bridge

    How can I tell if the popsicle sticks in my physics bridge are under compression or tension. The weight is put on top of the bridge
  40. P

    Which Design Should I Use for a Paper Bridge

    I'm trying to build a bridge but I have no clue where to start. I need to make a poster first but I don't know which design to use. I have found a website with the exact same project I need to make. For all the details, please go to www.gravitykills.net. It has to be made of paper, hold...
  41. D

    Building a Strong Popsicle Stick Bridge: Tips and Tricks

    Hi, I've got to build a popsicle stick bridge for my Physics class. I have an idea of what I'm going to do, I just need tips, suggestions and thoughts. Requirements/restrictions: Width: Minimum 8cm Length: Minimum 55cm Thickness: Max 4cm Should be able to hold a minimum of 100 pounds...
  42. J

    If you jump off a bridge 50m above the water does the water need to be 50m deep?

    how deep would it have to be proportionally to how far you fell?
  43. M

    Finding Vg with Wheatstone Bridge: R1=40, R2=70, R3=50, R4=20

    1. I am having trouble finding the Vg for a problem involving a Wheatstone Bridge circuit. If I am labeling the problem correctly, R1=40, R2=70.0 R3=50.0 and R4=20.0. Voltage - in = 20.0V I am using the formula: ((R1*R3) - (R2*R4) *V-in) / (R1 + R2) * (R4+R3) to find Vg between points B...
  44. I

    Solve Wheatstone Bridge: Homework Statement & Equations

    Homework Statement I think I got part A. I'm complete lost with b -d and help would be greatHomework Equations https://www.physicsforums.com/attachment.php?attachmentid=10986&d=1190644998 The Attempt at a Solution It think part d is ∆V = [(∆R1 - ∆R2 + ∆R3 –∆R4 ) / 4R ] * Vo But I'm not sure...
  45. M

    Effective reisistance of an unbalanced wheatstone bridge.

    Homework Statement I have an exam and therefore quick help is requested. I need a simple way to find out the resistance of an unbalanced wheatstone bridge. Suppos R1=2 ohm, R2=1 ohm, R3=4 ohm, R4=4 ohm and the connecting bridge's R5=10 ohm. Here, R1/R2 is not equal to R3/R4. Then How to...
  46. J

    Can You Solve the Bridge Troll Puzzle?

    Here is a puzzle that a camp counselor asked me. But unfortunately he forgot to tell me the answer as he said he would at the end of the camp. I checked online at lots of sites but none had this brain teaser. So i hope one of you guys can pm me the answer. Here is the brain teaser. There is a...
  47. L

    PSpice Simulation - Bridge Rectifier

    Hi, I'm having a problem while running a simulation of a Bridge Rectifier on PSpice. This is my circuit schematic: http://img521.imageshack.us/img521/276/q1tasks2schematicsxp3.jpg Vs is at 15sin(100*pi*t). And this is the input and output waveforms plotted by PSpice...
  48. K

    Circular Motion of car over a bridge

    I. A hump back bridge has a radius of curvature of 40m. Calculate the max speed at which a car could travel across the bridge without leaving the road at the top of the hump. I realized that weight - contact force at the top would give the resultant centripetal force. But i have no...
  49. Astronuc

    I35W Bridge Collapse - Potential Flaw

    This belongs under Civil/Structural, but is a Mechanical Engineering issue as well. Potential Flaw Seen in Design of Fallen Bridge, NYTimes, Aug 9 http://www.nytimes.com/2007/08/09/us/09bridge.html The use of Gussets is standard in steel bridges. They form the joints shared by various...
  50. R

    Resonance and bridge collapses

    I remember the discussion of resonance from physics class a long time ago because of the illustration of the collapse of the Tacoma Narrows Bridge which was presented as a result of resonance resulting in part from the fact that the bridge's two suspended spans were the same length...
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