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. F

    Can A and B be equal in the region between x=0 and x=a?

    Homework Statement write the solutions to the S.E in regions x<o and x between o and a C:\Users\karthik\Desktop Homework Equations I believe psi(x)= e^ikx+Re^-ikx in x<0 and psi(x)=Ae^iqx+Be^-iqx for x b/w o and a. The Attempt at a Solution My question is, since there is...
  2. B

    Infinite potential barrier Q

    Just a quick question. Solving the Schrodinger equation (time-independent) for an infinite potential barrier, I end up with two wavefunctions. In region I, V(x)=0 \Rightarrow\psi(x)=Acos(\frac{\sqrt{2mE}}{\hbar}x)+Bsin(\frac{\sqrt{2mE}}{\hbar}x) In region II, V(x)=\infty...
  3. E

    How Is Barrier Height Calculated in Physics?

    I don't want to double post, so I'll just post the link to my original physicsforums.com post since my question is probably more of a physics than engineer question --> https://www.physicsforums.com/showthread.php?t=274887" Thanks for any help, Paul
  4. E

    How Should Dopant Density Influence Barrier Height in Schottky Diodes?

    Hi, Is this the correct place to post this? Perhaps it's more of a physics question. I'm trying to write a small program to design basic Schottky diodes. I'm using the following equation to calculate the current produced by a small applied voltage, far below Vt --> I = A * Aast * T^2 *...
  5. wolram

    ETH Zurich Researchers Break 1 Million RPM Motor Barrier

    http://www.sciencedaily.com/releases/2008/11/081114081213.htm Up to now, industrially-deployed motors have normally reached 250,000 revolutions per minute. Now, however, researchers from ETH Zurich’s Department of Power Electronics have developed a drive system in cooperation with its...
  6. J

    Energy Barrier to Rotation in 1-Iodopropane

    What's an energy barrir to rotation? I have data on the enrgy at anti and gauche conformations of 1-iodopropane. I have also graphed the data (steric energy vs dihedral angle) from the graph, do I just subtract the trough at anti from the trough at gauche? so from anti to gauche, it'd be...
  7. S

    Quantum Barrier Potential (should be easy)

    Homework Statement A 10-eV electron is incident on a potential barrier of height 25eV and width 1 nm. Use equation 6-76 to calculate the order of magnitude of the probablity that the electron will tunnel through the barriers. Repeat with width .1nm Homework EquationsEquation 6-76 is: E =...
  8. L

    QM Free Particle Approaching Infinite Barrier

    Solved... i think. It's just Psi(x) = B sin kx Homework Statement Consider a free particle psi(x) = A*e^(ikx) approaching an infinite barrier from the left: V = 0, x < 0 and V = oo, x >= 0. For this problem use only the time-independent Schrodinger Equation. a. Find the probability of being...
  9. D

    Electron beam in a Potential Barrier

    Problem An electron beam is sent through a potential barrier 4.5 \AA long. The transmission coefficient exhibits a third maximum at E = 100 \text{eV}. What is the height of the barrier? Solution Answer: 95.8219 \text{eV} We know that the transmission coefficient reaches a maximum of 1 only...
  10. K

    Unfolded to Folded: Exploring the Entropic Free Energy Barrier

    I have a question about protein folding. I have heard that there is a free energy barrier to overcome in going from the unfolded (ensemble) to folded states, and that this barrier is largely entropic -- i.e., as the (idealized, general) protein starts to fold, it loses more in entropy than it...
  11. K

    Tunneling through a PE barrier

    I'm still in Intro Physics, and I'm a little perplexed by the concept of tunneling. An alpha particle escapes the nucleus by overcoming a potential energy barrier created by Coulombic repulsion with the protons of the nucleus, but this is a spontaneous process and does not require E input...
  12. S

    Particle Penetrating through a Potential Barrier

    Homework Statement hey all! i have a relli urgent question that needs to be answered in as much detail as possible...hope someone can help... Q: How is a particle, with energy of lower value than the potential barrier, able to penetrate through the barrier? (ans cannot have reasons like...
  13. T

    Delta potential barrier in a box

    hi,... i unfortunately couldn't find a solution to this problem although it seems like a classical textbook problem... how can i solve the (time independent) schroedingerequation for the following potential V(x) = \infty for x<=-1 V(x) = a\delta(x) for -1<x<1 V(x) = \infty for x>=1 so at x=0...
  14. J

    Energy changes of a particle tunneling through a barrier

    Hi everyone, just wanting to know if anyone could help me out about particles tunnelling through square barriers with inital energy E<Vo. Does the energy of the particle change as it tunnels through the square barrier?
  15. S

    How to simulate a potential barrier?

    Hi, I am doing simulations on a particle in some potential together with a fluctuating force and friction. To do that, I use the Langevin equation with the fluctuating force being a random number from a normal distribution with a temperature-dependent variance. I use a Verlet-algorithm for...
  16. M

    QM - one-dimensional barrier - a simple step

    analyzing the simple-step scattering problem for E<V, we find that the solution to the schroedinger equation is: PHI(left) = Aexp(ikx)+Bexp(-ikx) PHI(right) = Cexp(-qx) Continuity of the function and it's derivative at x=0 gives the relations between the parameters A, B and C. Solving the...
  17. N

    Barrier Tunneling and Kinetic Energy

    1. Homework Statement b). Find the kinetic energy K (sub t), the proton will have on the other side of the barrier if it tunnels through the barrier. c) Find the kinetic energy K (sub r), it will have if it reflects from the barrier. Variables: Transmission Coefficient (T) T= e^-2bL T...
  18. N

    Barrier Tunneling and Kinetic Energy

    1. Homework Statement b). Find the kinetic energy K (sub t), the proton will have on the other side of the barrier if it tunnels through the barrier. c) Find the kinetic energy K (sub r), it will have if it reflects from the barrier. Variables: Transmission Coefficient (T) T=...
  19. D

    Barrier tunneling - Intro to QM

    Homework Statement Ok, maybe I'm slow at grasping this, but why is the potential energy U of an electron while it is tunneling through a 1 dimensional potential barrier of height V0 = V0? Homework Equations Schrodinger equation in 1D (using semiclassical approximation) The Attempt...
  20. I

    Solving arbitrary potential barrier problems

    I am doing a computational project in my undergraduate Quantum Physics course on tunneling through a potential barrier. But, it's an irregular potential barrier, so I cannot simply use the results from a textbook. The first diagram, with corresponding wave equations, are shown in the first...
  21. N

    Why Does an Infinite Potential Barrier Affect Particle Wavefunctions?

    Homework Statement find the wavefunction of a particle in a potential V(x)= 0, |x|< a V, |x|< b (V>0) (Infinity), |x|>=b ground state energy 0<=E<=V Homework Equations The Attempt at a Solution i know the wavefunction has to be equal to zero at...
  22. S

    Coulomb barrier in alpha decay

    Can you gurus help me understand in a qualitative way the nature of the Coulomb barrier as it applies to alpha decay? I can intuitively appreciate the Coulomb barrier as it applies to an incoming charged particle, but resources I have been reading apply the same term to the barrier felt by...
  23. E

    Scientists claims light speed barrier broken

    Source
  24. G

    Lowering of activation barrier

    Hi, It is stated that changing the medium - water to ethanol f.ex - the experimentally measured rate enhancement is 10^6 fold which leads to a lowering of the activation barrier of \approx 9 kcal/mol. I don't quite understand which parameters I am missing in order to calculate that? Any help...
  25. N

    Quick Potential Barrier tunnelling question

    I am dealing with the classic problem of a potential barrier of finite width, with a particle tunneling through, in the case of E < V. I am to calculate the transmission/reflection coefficients, and we first start off with the wavefunctions for the three regions. Before the barrier, we...
  26. D

    Can an Infinite Potential Barrier Conserve Energy in Real Life Scenarios?

    I got a question about an infinite potential barrier. If a particle with a momentum p travell through an infinite potential barrier, how can the energy be conserved, thus how can the particle have the same momentum after passing the barrier? Does there exists any real life example?
  27. N

    Potential Barrier (Q.M. vs Classical Phy.)

    If you have a Potential Barrier V (width a) and particles incident on left with energy E where E>V, are the following true: Classical Physics: - All particles will be transmitted past the barrier - It cannot be reflected because that would mean it has negative E which is not possible...
  28. N

    Potential Barrier (Q.M. vs Classical Phy.)

    If you have a Potential Barrier V (width a) and particles incident on left with energy E where E>V, are the following true: Classical Physics: - All particles will be transmitted past the barrier - It cannot be reflected because that would mean it has negative E which is not possible...
  29. A

    What is the maximum speed the car can have to avoid hitting the barrier?

    Hi there, I am a grade 11 student, learning physics. Homework Statement A driver of a car going 90km/h suddenly sees the lights of a barrier 40.0 m ahead. It takes the driver 0.75s before he applies the brakes and the average accelleration during braking is -10.0m/s2. a) Determine...
  30. C

    Coulomb Potential Barrier: Is This Calc Right? What's fm?

    The Coulomb potential barrier of a system of two nuclei X and Y is approximately given by VC = ZX*ZY*e2/RN where ZX and ZY are the charge numbers of the nuclei, e2 = 1.44 MeV*fm, RN = (AX1/3+AY1/3) × r0 is the sum of the nuclear radii. r0 is a constant usually estimated to 1.2 to 1.3 fm and AX...
  31. M

    Does a Galactic Barrier Exist? Ask Here

    Off course we should not take too seriously what we read in Sci Fi books. I've just been to lazy to do any research into the concept of a galactic barrier which was introduced to me in a trilogy of books called the 'Q Continium' by Greg Cox. So if anyone knows if such a barrier does exist then...
  32. J

    Potential barrier, wave function, and probability

    I have a couple questions about finite potential barriers that I can't seem to figure out on my own... 1) Why does the real part of the wave function collapse inside the barrier (square, rectangular, barrier with V less than the energy of particle)? It seems to me that there should be some...
  33. J

    How to Calculate Transmission Coefficient for a Quantum Rectangular Barrier?

    Ok, so I've been dealing with this problem for a while and can't figure it out. (I tried to clean it up, but I don't know LaTeX, hopefully it is more clean in post #2; problem stated in #1, and my work in #2) --Consider a (plane-wave) particle tunneling through a rectangular barrier...
  34. A

    Barrier Potential Question: Understanding Energy and Barrier Interactions

    Question: What happens when the energy of the state is exactly equal to the barrier it hits? Say the particle is traveling to the right and hits the barrier. Before hitting, you have your typical solutions, say Aexp(ikx) + Bexp(-ikx). After hitting, the V(psi) and E(psi) terms cancel...
  35. K

    Is There a One-to-One Barrier with Motors and Generators?

    a concept came up that that there is a one to one barrier with motors and generators. Is there such a thing? the only i am aware of would be relative to Newtons law (egual and oppisite reaction) if you put a number in is that the only number you have out? or can it be increase ( i thought that...
  36. H

    Another potential barrier question

    Since these seem to be popular around here these days, I thought I'd another to the mix :) "A particle of mass m and energy E > 0 approaches a potential drop -V0 from the left. What is the probability that it will be reflected back if E = V0/3? The potential energy is V(x) = 0 for x<0 and...
  37. C

    West Nile Virus, the blood brain barrier and the elderly

    My question is about West Nile Virus and why/how it is much more likely to cause encephalitis in the elderly. What I've found is that increased permeability of the BBB is what allows the virus to infect brain tissue which is how the majority of neurological damage is done. The rest of the...
  38. S

    Wave Function for Delta Function Barrier with E<0

    Given a delta function barrier located at x=0: V(x) = +a * delta(x) If you have a particle incident from the left with E<0, what does the wave function look like?? I have trouble with this because I thought the particle energy needed to be greater than the minimum potential (E > Vmin) for...
  39. N

    Musings on the physicists/mathematicians barrier

    After having spent some time trying to learn differential geometry and differential topology (my background is in physics phenomelogy) I can`t help making the following observation. I think it is harder to learn the maths starting from a background in physics than learning the math from...
  40. S

    Gravity Barrier: Facts & Explanation

    gravity barrier?? Hello all...first post I have a question about a "gravity barrier" that exists. I was in a discussion about the space shuttle launch that took place a few weeks ago and somehow we got on the subject of a gravitational barrier. Meaning the shuttle had to break at 4000 mph...
  41. W

    Light Barrier: Breaking the Speed of Light?

    Hi, just got into the topic of relativity and got curious. Is it possible to break the light barrier similiarly to the sound barrier? I have just found an article that someone had done it. http://www.lastek.com.au/light.htm What are your views on this?
  42. JasonJo

    Breaking the Barrier: Pursuing Math/Science as a Lifelong Thing

    How do you break the barrier from getting good grades to truly pursuing mathematics/science as a lifelong thing? i do what i like to call "good enough to get an A" but i want to step it up and reach that next level, where it's more research oriented. any thoughts?
  43. S

    What is the best estimate for the penetration distance in quantum mechanics?

    We have a particle of energy E crossing a potential jump at x=0. for x<=0, V=0, for x>=0 V=V1 We get a wavefunction for x>=0 psi(x) = exp(-iEt/hbar)*exp(-Kx) where K = (2m(V1-E))^0.5/hbar N.b E<V1 so classically we get no transmission we are asked to estimate the penetration distance, and...
  44. L

    Quantum - Potential Barrier

    Hi there, Was wondering about the potential barrier problem when Eo>V. I have figured out the expression for the Transmission coeffient (after a lot of algebra) and am now wondering, what happens when I vary the width of the barrier, obviously there is greater transmission when the barrier...
  45. Q

    Why does a jet look like this when it breaks the sound barrier?

    This pic is really cool, it looksl ike a cloud. I'm only 17, so don't know much physics, i hope someone can explain this in an easier way. Why does it look like a cloud
  46. S

    Understanding Image Force: Barrier or Reducer?

    i don't quite understand how it operates. from what i read it seems the image force is part of the barrier. but the textbook says it reduces the barrier. which is which?
  47. K

    Barrier Tunneling: Proton Transmission Coefficient

    I can't work out what I am doing wrong in this question. Anyways, here it is: A 3.0 MeV proton is incident on a potential energy barrier of thickness 10fm and height 10 MeV. What is the transmission coefficient T. And here is what I have tried: T=e^(-2bL) b=\sqrt{\frac{8\pi^2m(U_b-E)}{h^2}}...
  48. C

    Units in a quantum barrier problem

    I have a quesion regarding a quantum physics assignemnt, I wonder what units I should use when calculating the transmission coefficient of a quantum barrier problem. I have got the following expression: T = \frac{4(E+V_0)}{(2E+V_0)cos^2a\sqrt{\frac{2m}{\hbar^2}(E-V_0)} +...
  49. T

    Time and the Sound Barrier: How Fast is Too Fast?

    When an object breaks the sound barrier, sounds "lag" behind that object as it travels faster, theoretically the same can be said for light. Would this work the same for time? If you exceeded whatever limit this barrier has would time "lag" behind you?
  50. S

    Developing a rubbery serpentine wall as a highway median barrier

    I am developing a rubbery serpentine wall as a highway median barrier and I need to know the tensile strength necessary to hold against a 4400 lb pickup moving 62.5 mph. Using an excel spreadsheet and iterations, I subtract the momentum of the wall from that of the pickup at 2 foot intervals...
Back
Top