What is Barrier: Definition and 260 Discussions

Traffic barriers (sometimes called Armco barriers, also known in North America as guardrails or guard rails and in Britain as crash barriers) keep vehicles within their roadway and prevent them from colliding with dangerous obstacles such as boulders, sign supports, trees, bridge abutments, buildings, walls, and large storm drains, or from traversing steep (non-recoverable) slopes or entering deep water. They are also installed within medians of divided highways to prevent errant vehicles from entering the opposing carriageway of traffic and help to reduce head-on collisions. Some of these barriers, designed to be struck from either side, are called median barriers. Traffic barriers can also be used to protect vulnerable areas like school yards, pedestrian zones, and fuel tanks from errant vehicles.
While barriers are normally designed to minimize injury to vehicle occupants, injuries do occur in collisions with traffic barriers. They should only be installed where a collision with the barrier is likely to be less severe than a collision with the hazard behind it. Where possible, it is preferable to remove, relocate or modify a hazard, rather than shield it with a barrier.To make sure they are safe and effective, traffic barriers undergo extensive simulated and full scale crash testing before they are approved for general use. While crash testing cannot replicate every potential manner of impact, testing programs are designed to determine the performance limits of traffic barriers and provide an adequate level of protection to road users.

View More On Wikipedia.org
Recent contents Top users
  1. S

    How Does the Filtration Barrier at the Kidney Work?

    Red-capillary Purple- Basement membrane Blue-podocyte Hello everyone, Now my question is after something if filtered from the capillary how does it go to the podocyte. The basement membrane looks too thick with no pores to me, it seems to be blocking the passage of molecules. Thanks :smile:
  2. R

    Potential step with infinite potential barrier (D.A.B Miller problem 2.8.6)

    Homework Statement We have a potential structure as follows: from z=negative infinity to z=-b, the potential is 0. At z=-b, the potential jumps up to some V_0. Then, at z=0, there is a potential barrier of infinite height. I need to solve for the magnitude of the reflected wave (i.e. the wave...
  3. mugaliens

    Effect on the Great Barrier Reef - Flooding and Cyclone Yasi

    I never made it down under to snorkel the Great Barrier Reef, but I've snorkeled other places around the world, and marvel at how some reefs seem to be teeming with life while others appear on the verge of death. I'm curious as to the effects all the flooding and now Cyclone Yasi might have on...
  4. M

    Breaking the sound barrier underwater?

    I know it may not even be mechanically possible to reach the speed of sound underwater (1,484 m/s); but this is just a theory. After discussing with several people, what would happen if a submarine was to break the sound barrier underwater, a couple of interesting theories arose. Going...
  5. D

    Fusion reaction energy and columb barrier

    I'm currently studying Freidberg's plasma physics and fusion energy book, I've heard that Fusion between Deutrium and tritium is most suitable for a fusion reactor and how columb barrier plays its role....my question is what happens when two neutrons fuse together? do they face columb collision?
  6. A

    Throwing a Baseball to Break the Sound Barrier?

    How fast must a human throw a baseball in order to break the sound barrier? I know a jet breaks the sound barrier at approximately 750 mph but would it be the same for a human?
  7. S

    What is the correct math notation for the Coulomb Barrier?

    I am trying to find out what is the correct way to write the mathematical demarkation for the Coulomb Barrier. You know, if I wanted to write the symbol for the radius of the coulomb barrier. If anyone could show me it in the correct font that would be great. NO, this isn't for...
  8. H

    Solving Particle Incident on Rectangular Barrier

    b]1. Homework Statement [/b] Consider a particle of mass m incident on a rectangular barrier with a potential V(x) = V0 for 0 \leq x < w V(x) = 0 otherwise, where V0 is a positive constant. The particle has an energy E > V0. Find expressions in...
  9. Z

    Potential barrier problem

    Homework Statement a particle of kinetic energy E is incident from left on a potential barrier,height U, situated at the origin.the barrier is infinitely wide and E>U obtain an expression for the reflection coefficient R of the particle as a fuction ratio e=E/U Homework Equations...
  10. maverick280857

    Delta well + infinite barrier -> bound state

    Hi, I'm trying to understand the quantum mechanical solution to this potential: V(x) = \left\{\begin{array}{cc}\infty & \mbox{ for } x < 0,\\-\lambda\delta(x-d) & \mbox { for } x > 0\end{array}\right. A particle of mass m is constrained to move on the half straight line \{x \in \mathbb{R}: x...
  11. J

    Perforated Radiant Barrier Insulation

    Will installing perforated radiant barrier insulation in the attic reduce the power bill significantly.
  12. P

    Barrier potential representation

    Having trouble drawing the wave representations for this diagram. [PLAIN]http://img156.imageshack.us/img156/94/diag.png I'm not sure what the incident and reflected waves should look like. The question is asking to draw the waves in each region. I understand how to calculate the waves just...
  13. A

    Can a propeller driven aircraft break the sound barrier?

    Hope this is the right place for this question, but it is very inetresting to me so I wanted to ask some experts. Can a propeller driven aircraft break the sound barrier? My answer, no. Any opinions will help Thanks
  14. J

    Is the particle able to penetrate finite barrier?

    Let's have a kind of step potential, V=infinity, where x\leq0, V=constant, where 0\leqx\leqa, V=zero , where x\geqa. Then, my question is that when the energy of the particle is lesser than zero, which means that the particle is in the bound state, is there a probability of getting...
  15. M

    Single barrier with impurity as a 1D resonant tunneling model

    Friends, I am trying to consider an impurity which can be viewed as a 1D resonant-tunnelling problem. I gather that the transmission coefficients TL and TR will decay exponentially from the impurity to the edges of the barrier. However, I am unsure how to predict how the peak & area of T(E)...
  16. O

    Potential Barrier in Infinite Well: Equal Amplitudes Both Sides?

    Homework Statement The well is set up exactly like this https://www.physicsforums.com/showthread.php?t=397977&highlight=potential+barrier+inside+an+infinite+square+well. It is basically a infinite potential well with a barrier in the center. Basically I've got solutions for regions 1, 2...
  17. P

    Solving Delta Potential Barrier Problem with Schrodinger Equation

    Homework Statement In delta potential barrier problem Schrodinger equation we get \psi(x)=Ae^{kx}, x<0 \psi(x)=Ae^{-kx}, x>0 We must get solution of lim_{\epsilon \rightarrow 0} \int^{\epsilon}_{-\epsilon}\frac{d^2\psi}{dx^2}dx Homework Equations The Attempt at a Solution lim_{\epsilon...
  18. R

    Electron beam, potential barrier

    Electron beam with kinetic energy E_{k} = 10 eV strikes a positive potential barrier V_{0} and the kinetic energy after the beam has passed through the barrier is E_{k} = (10 eV -V_{0}). How big potential V_{0} is needed so that 40% of the electron beam is going to be reflected? What...
  19. N

    Potential Barrier - Special Case

    Homework Statement A beam of particles, each of mass m and kinetic energy E, is incident on a potential barrier V(x) = V_0 \; \; for \; \; 0 \leq x \leq a \; \; \; \; \; \; \; \; \; = 0 \; \; for \; \; x < 0 \; \; and \; \; x > a E = V_0 \; \mbox{is the special case} The part...
  20. R

    Elektron beam strikes in potential barrier

    Electron beam with kinetic energy E_{k} = 10 eV strikes a positive potential barrier V_{0} and the kinetic energy after the beam has passed through the barrier is E_{k} = (10 eV -V_{0}). How big potential V_{0} is needed so that 40% of the electron beam is going to be reflected? What...
  21. C

    Breaking Through the Coulomb Barrier: Solving an Equation

    im generating potentials, however the coulomb is proving tricky. stumbling block is finding a way to write A coth(2x) + B cosech(2x)= (A+B)/2 tanh(x)+(A_B)/2 coth(x) i am at the RHS and need to get the tanh to come out which I am told can be done. the a's and b's might not be quite right...
  22. R

    Number of collisions with potential barrier

    Homework Statement In a particular atom, an alpha particle makes N collisions with a potential barrier in each second. The transmission coefficient at the barrier is 1.0e-15. In one second, 2.0e18 alpha particles are emitted from a group of 3.0e23 radioactive atoms. Find N. Homework...
  23. O

    Schrodinger's Equation, Potential Energy Barrier U>E

    Homework Statement Consider particles incident on a potential energy step with E<U. (That is, a particle with total energy E travels along one dimension where U=0, then crosses, at point x=0 into a region where U>E.) (The particle is incident on the potential energy step from the negative x...
  24. K

    How do I derive T (transmission) in a rectangular potential barrier with E > V0?

    Barrier potential, E> V0 V(X) = 0 ( x < 0 ) = V0 ( 0 < x < a ) = 0 ( x> a ) Psi(x)1 = Aexp[ik1x] + B exp[-ik1x] Psi(x)2 = Cexp[ik2x] + D exp[-ik2x] Psi(x)3 = Fexp[ik1x] + G exp[-ik1x] ( K3= K1 so I put k1 ) and G = 0 because there is no reflection, I used B.C...
  25. S

    Transmission Coefficient of a Rectangular Square Potential Barrier

    If you have a rectangular square potential barrier of some height, say \lambda/L, and thickness L, what is the transmission coefficient and what is its value in the limit that L goes to 0? Thus you have the height of the barrier going to infinity, while the width goes to zero... Assuming...
  26. S

    Quantum Tunneling Probability for a rectangular barrier

    Hey everyone, For my a research project on quantum tunneling I have to tie in math somehow, so I was wondering if anyone could help me learn to calculate the probability of a wave (preferably like an electron or electrical voltage) of some sort passing through a rectangular barrier, which is...
  27. R

    Finite Square Barrier Scattering Example with Reflection Coefficient Calculation

    Hello to all, I am looking at a scattering example in my book. A particle is incident from the left with energy E > Vo. The barrier is of width L, and located between x = 0 and x = L. The solutions to the time-independent Schrodinger equation in eacch of the regions comprising the left...
  28. K

    Potential barrier in nuclear fusion

    Homework Statement To calculate the height of the potential barrier for a head on collision between two deuterons given that each deuteron is a sphere of radius R Homework Equations Potential of the first deuteron at a distance of 2R from it =V = ke/2R where k = 9 * 10^9 , e= 1.6 *...
  29. S

    Projectile thrown at a barrier

    Homework Statement A projectile is thrown from the horizontal ground with a speed of 40 m/sec at an angle with the horizontal of 30 degrees. At what height will the projectile strike a high barrier located at a distance of 85m from the firing point? Homework Equations ok so: point A is...
  30. I

    Solving Schrodinger Equation for Finite Potential Barrier

    Homework Statement I am trying to find the coefficients in a Schrodinger equation approaching a finite potential. https://www.physicsforums.com/showthread.php?t=203385 It is a problem similar to this, except a little easier. In my case, though, there is no V1 as shown in the picture at the...
  31. R

    Quantum Tunneling: Observed properties of the particle within the barrier.

    Hi. Firstly, can a particle every be found within the potential barrier? I've used the search function to look for an answer for this question, but I didn't really get anything conclusive. However, from what I gather, since there is a probability associated with it being 'found'(meaning it...
  32. D

    Quantum - Square barrier (help)

    Question: Determine the transmission coefficient for a rectangular barrier. Treat separately the three cases E<0, E=Vo, E>Vo (note that the wave function inside the barrier is different in the three cases. and V(x) = Vo > 0 for -a < x < a = 0 for |x| > a I...
  33. I

    The particle INSIDE the barrier

    So I know this topic of tunneling has been discussed hundreds of times on this forum, but I simply cannot find nor deduce an answer to a burning question I have about what happens exactly INSIDE the barrier and how to describe it (preferably in layman's terms.) The problem is basic: A...
  34. R

    Solving the 1-D Potential Barrier Problem - Rajasekhar

    HI,all This is rajasekhar , Please guide me how to solve below problem. An electron moves in a one-dimensional potential of width 8 angstroms and depth 12eV then how to found number of bound states present? Thanks&Regaurds
  35. R

    Solve 1-D Potential Barrier: Electron, Width 8 Angstroms, Depth 12eV

    HI,all This is rajasekhar , Please guide me how to solve below problem. An electron moves in a one-dimensional potential of width 8 angstroms and depth 12eV then how to found number of bound states present? Thanks&Regaurds
  36. W

    What is the ratio of energy to barrier height for a 0.43 reflection coefficient?

    Homework Statement A particle of energy E approaches a step barrier of height U0. What should be the ratio E/U0 so that the reflection coefficient is 0.43? Homework Equations R=(k1-k2)^2/(k1+k2)^2 <--------reflection coefficient The Attempt at a Solution I am completely stumped...
  37. E

    Solve Potential Barrier Homework: Find Transmission/Reflection Coeff.

    Homework Statement Find the transmission and reflection coefficients for: V(x)=\left\{\begin{matrix} V_0, & -a\leq x\leq a\\ 0, & elsewhere \end{matrix}\right. Homework Equations \frac{-\hbar^2}{2m}\frac{\partial^2 }{\partial x^2}\psi+V\psi=E\psi The Attempt at a Solution I...
  38. M

    Gaussian Wavepacket Tunnel Through double barrier

    Hello, I was trying to design a movie in Matlab. A Gaussian wave packet moves toward double barrier then some wave reflect and some pass out from the barrier . i design the double barrier in Matlab. but don't know how to make movie in Matlab with Gaussian wavepacket. can you help. Do u have...
  39. S

    Can Insulation and Heat Reflective Materials Work Together for Fire Safety?

    Sorry for such a simple question, but what are the differences between using insulation and heat reflective material? What is the effective of using them together? In my case I want to shield flammable foam insulation from melting or catching fire from a nearby heater. Will covering the...
  40. R

    What exactly is barrier tunneling and potential barrier?

    How can we create a potential barrier? And how does it exactly acts as barrier in electron transfer?
  41. E

    Can you break the sound barrier under water?

    Has it be done? And what's the sound barrier in space and can it be broken?
  42. C

    Breaking 10 second barrier too difficult for Whites, Asians and East Africans

    http://en.wikipedia.org/wiki/10-second_barrier
  43. A

    The rate of cooling of a material in air, or with no barrier between materials

    I'm unsure how to approach this, as solid blocks of materials next to each other (e.g. steel and air) with no barrier inbetween as shown on http://en.wikipedia.org/wiki/Thermal_conductivity "x" would equal zero, this can't be correct. Is there another equation relating temperature difference...
  44. S

    Barrier transparency and quantum tunnling

    Dears what is "barrier transparency" and what is "quantum tunnling" in fusion? Regards
  45. D

    Total Transmission Across Finite Barrier Potential with E>V

    Homework Statement A beam of electrons of KE = 100 eV is incident from the left on a barrier which is 200 eV high and 10 nm wide. If the momentum spread is sufficiently narrow, then a simple plane wave is a good approximation. Recall that the mass of an electron is mc2 = 511 keV. ....._____...
  46. F

    Solving Potential Barrier Homework Problem

    Homework Statement Consider the diagram described by: http://filer.case.edu/pal25/well.jpg If a particle with E = \frac{-\hbar^2 q^2}{2m} comes in from negative infinity with amplitude 1, what is the wave function for negative x? Oh and V(x) < -a and > a = 0 Homework Equations...
  47. M

    Finite Square Well/ Barrier

    Homework Statement Determine the transmission coefficient for a rectangular barrier. Treat seperately the three cases E<Vo, E>Vo, and E=Vo.Homework Equations V(x)= +Vo if -a<xa V(x)= 0 otherwise Transmission coefficient=(amplitude of transmited wave)2/(amplitude of incoming wave)2 I am also...
  48. T

    Energy needed to tunnel through a potential barrier

    Homework Statement An electron approaches a potential barrier 10 eV high and 0.5 nm wide. If the electron has a 1% chance of tunnelling through, what must be its energy? Homework Equations don't know how to put equations in eg how do i get something like alpha and theta etc...
  49. D

    Quantum Well & Barrier w/ Phase Shift

    Homework Statement V(x) = \inf if x \leq 0 = -V if 0 < x < a = 0 if x > a NOTE: E>V Find the wave functions in each region and the stated phase shift. Homework Equations Schrodinger Eq. Instructions note that wave functions are: \Psi_I = A\sin{kx} \Psi_{II} =...
  50. D

    Quantum-electron tunneling barrier

    assuming that the electron has an incident energy of 8eV and that the barrier is of height Vo=13eV and width L=5x10-10m calculate the probability that the electron will be able to tunnel through the barrier.Relevant equations= k = (sqrt(2m(V-E)) /h-answer (sqrt(2x9.1x10-31(13-8)x1.6x10-19)x2pi...
Back
Top