What is Wall: Definition and 756 Discussions

A wall is a structure and a surface that defines an area; carries a load; provides security, shelter, or soundproofing; or, is decorative. There are many kinds of walls, including:

Walls in buildings that form a fundamental part of the superstructure or separate interior rooms, sometimes for fire safety
Glass walls (a wall in which the primary structure is made of glass; does not include openings within walls that have glass coverings: these are windows)
Border barriers between countries
Brick walls
Defensive walls in fortifications
Permanent, solid fences
Retaining walls, which hold back dirt, stone, water, or noise sound
Stone walls
Walls that protect from oceans (seawalls) or rivers (levees)

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

    Momentum Conservation in Collisions

    Homework Statement A ball hits a wall with momentum p1. The book says the momentum "returned" by the wall equals -2p1 .. i.e. it doubles. What does that mean? Here's why I ask: If I throw a ball against a wall and it comes back and I catch it, I KNOW the momentum has not doubled just...
  2. L

    Quantum tunneling of a car through a wall

    Hi everyone Homework Statement I have to calculate the probablity that someone can tunnel a wall with a car. I have the mass of the car and the velocity and I know that the wall is 20 cm wide. But I have troubles estimating the potential of the wall. Homework Equations - The...
  3. T

    Found a math equation graffitied on a wall. What's it trying to say?

    Hello everyone, longtime reader, first time poster. A friend and I discovered this piece of math graffitied on an obscure laneway wall in Melbourne. I find it a bit mindblowing that someone would go to all this effort, particularly in a place where very few people are going to see it. As you...
  4. D

    Computer design of retaining wall design

    I got material from this site that I used for my proposal(for the literature). Have a time limit to submit the program on the day of examination (1st Dec, 2012). I need a check and correction I attach copy of the flow chart and diagram. C PROGRAM FOR RETAINING WALL STABLITY AND DESIGN C...
  5. E

    Sphere on an incline plane against a wall

    Homework Statement Find all of the forces acting on the sphere. The problem must be solved in variables. A sphere, mass m, is resting on an incline plane at θ relative to the horizontal. The sphere is also resting against a perpendicular wall relative to the horizontal. Gravity = g.Homework...
  6. O

    Calculating optimum thickness of the insulation for composite wall

    Homework Statement A wall is required to be insulated by embedding wood within concrete. the total thickness of the concrete and wood are 10cm and 1 cm respectively and are fixed due to structural constraints. determine the minimum heat leak into the room if the location of the wood can be...
  7. K

    Ladder leaned against a wall; forces

    Homework Statement There is a 5m ladder leaned against a wall, making an angle of θ with the ground. The ground is rough (getting at friction), and the wall is frictionless. Here's an ASCII attempt: |\ |..\ |...\5 |...\ |...θ\ We want to make a force diagram for the ladder, then find the...
  8. M

    I've finally hit a wall with math

    Hi folks, I'm just going to cut to the chase. I'm not sure I can survive my Chemistry major, as I am being tormented by my performance in math. I need to take 5 math courses (Calc I, II, II, LA I, and ODE I) of those I've completed two Calc I (84%) and LA I (51%) and am now taking Calc II and...
  9. Crazymechanic

    Magnet on Metal Wall: Exploring the Work of Magnetic Fields

    Hi a simple question that struck my mind.Let's imagine a ferrite magnet from a old loudspeaker now let's put that magnet on a metal wall , or door , the magnet holds to the metal vertically and any other material put similar would just fall off so t seems to me that the magnet or the magnetic...
  10. N

    MATLAB Analyzing Wall Thickness vs Force Data Sets

    Attached are three figures. The problem in question essentially involves extracting data from a .CSV (MS Excel) file and .mdb (MS Access) file which I have done already but not correctly. Data set #1: gives me 'Wall Thickness vs. Time' ( [3400 - 8200] s , [0,1] in.) as shown in figure3.jpg...
  11. F

    Handymen - info needed for wall repair

    So we managed to damage a wall at our apartment: http://i.imgur.com/gi5b4.jpg Handymen of the forums, how would you repair?
  12. D

    Ricochet of moving / rotating block off a wall

    Thank you in advance for your help! The title pretty much says it all. I'm looking to write a 2D physics sim in which various objects can bounce off solid surfaces (without gravity). The objects are rotating and translating at a constant rate. We are dealing only with x and y - not z...
  13. P

    Forces of a wrecking ball against a wall at rest.

    Hello everyone, this is my first time posting to these forums, and my first time posting any online help regarding math. As you can imagine, this is a bit awkward and embarrassing for me. My textbook has no examples of the type of problem below and hours of googling has failed me. Hopefully...
  14. T

    Mr. H Falls from the Top of a Climbing Wall

    A 65 Kg Mr. H fell 8.0 m from the top of a climbing wall and he is going 12.52 m/s until he hits the mats. If the mats are 40 cm thick, how much force did they exert on him to prevent him from hitting the floor? I think you need to use the vf^2=vi^2 + 2a(df-di) formula to find the...
  15. arupel

    The Kantian Wall - The Meaning of Space, Time, and Mass in Modern Physics

    Some things have extreme simplicity, but because they sideways of our vision, they are unnoticed. Some things are so obvious, so close to us that they are almost invisible. This is a philosophical, not a scientific essay. It initially began as an exploration of belief, based on skepticism...
  16. S

    Pressure vessels, wall thickness

    Homework Statement 20 m3 of gas at a pressure of 25 bar is to be stored in a cylindrical pressure vessel 2 m long. Given the following information : The yield strength of the vessel material is 14,000 psi If a factor of safety of 5 is to be used, determine: (a) Whether the vessel should be...
  17. U

    Force of block pushed against wall

    Homework Statement A block of mass 20 kg is pushed against a vertical surface (see picture). The coefficient of friction, μ, between the surface and the block is 0.2. If θ = 30°, what is the minimum magnitude of P to hold the block still? Homework Equations f = force of friction = μN...
  18. T

    Average force exerted by ball on the wall

    Homework Statement A superball is to bounce elastically back and forth between two rigid walls at a distance d from each other. neglecting gravity and assuming the velocity of superball to be horizontal .Find the average force being exerted by the superball on each wall is ?Homework Equations...
  19. Feodalherren

    Tennisball bouncing on wall - momentum

    Homework Statement A tennis ball (m  0.2 kg) is thrown at a brick wall. It is traveling horizontally at 12 m/s just before hitting the wall and rebounds from the wall at 8 m/s, still traveling horizontally. The ball is in contact with the wall for 0.04 s. What is the magnitude of the...
  20. N

    How Do You Calculate the Force on Screws in a Rotating Cylindrical Vessel?

    The problem is the following: we have 2 half's of a cylinder and they are put together using 6 screws, forming a full cylinder. Inside there is water and we are asked to calculate the force on the screws when the cylinder rotates with constant angular velocity Ω. Using the equations of...
  21. S

    Learn How to Project an Image on a CRT Monitor with a Small Projector

    I wish to build a small projector . how to project an image on my crt monitor on screen.Is it possible.
  22. C

    Equilibrium - Ladder against wall

    Homework Statement A 7.0kg ladder is placed against a smooth wall so that it makes an angel of 72deg to the horizontal. A 56kg person stands 4.0m from the bottom of the ladder. What force does the wall exert on the ladder? What is the coefficient of friction between the ladder and the...
  23. V

    Wall Strength of a Shipping Container

    I'm going to bolt some hooks to the inside walls of 20ft and 40ft shipping containers. What I'm wondering is, what would be the easiest way to determine the stress on the corrugated steel walls, excerted on it by placing things on these hooks?. The hooks are 280mm apart and the force will be...
  24. Pengwuino

    Different devices charging on same wall plug

    Okay so, PF, here is my situation! I have my cell phone and my digital camera and they both came with those wall chargers where you plug in a USB cable into the actual wall plug. This allows you to use the same cable to charge off a wall or a computer. Now, I was wondering if I can use the plugs...
  25. P

    Safe to remove inner wall of pond or will it burst?

    Safe to remove inner wall of pond or will it burst?? 1.Problem I have a fishpond. It is raised 0.4m above the ground, the wall being interlocking wooden blocks. The blocks are all locked together all the way round so they could be picked up and put down somewhere else. The pond is 2.4m long...
  26. K

    Finding Reactions of Cantilever Beam Inserted Into Wall

    Homework Statement a cantilever beam 5 m long with a mass of 100 N/m carries a concentrated load of 1000 N at its free end. The end of the beam is inserted into a wall 0.5 m thick. What are the reaction on the beam. Homework Equations The Attempt at a Solution My problem is I...
  27. A

    Rigid body (rectangular) collision with wall

    Hello, I have a rectangular object with the following properties: Mass (m) = 1 units Moment Of Inertia (I) = 4.41 units initial velocity (v_{i}) = (5, 0) initial angular velocity (w_{i}) = 0 If the block collides with a solid rigid wall with distance vector r = (1.1, 1.4) from the...
  28. A

    Help with Calculating Wall Temperature of Air Cooled Condenser

    Hey my problem is related to air cooled condenser The condenser is for removing 5MW thermal power from steam at 350 C, the pressure is 170 kg/cm2. The average temperature of outside air is 95 C(inlet at 45 C and outlet at 145 C). the data is as follows: no of tubes : 182 tube od =25.4 mm tube...
  29. A

    How to calculate the minimum pipe wall thickness in this scenario

    Hey guys, Hope you can help me with the following practical problem I am facing right now. I plan to build a pipe system in which ethanol (vapor/liquid) is being conducted at pressures from 1 atm to 10^(-2) atm. What would the minimum pipe wall thickness be if the pipe material was a)...
  30. E

    How Fast Must a Car Drive to Avoid Slipping on the Wall of Death?

    Homework Statement I guess wall of death mechanic is not easy. Moving to the question. We have a mass of 1000 kg driving on the wall of death with radius 20 m. TO avoid slipping down the wall, the friction between the tyres.. Asuming that the mass is something like a car for example. Anyway...
  31. H

    Accounting for Compressive Forces in Thin Wall Pressure Vessels

    Description is in the image as well as the question. I was wondering for a) do i need to take into account the compressive forces that is acting on the vessel? Cheers
  32. S

    Attraction between a wall and a magnet

    Hi All, I was wondering: for a given size and strength magnet sticking to a wall of a given material and surface area, does the thickness of the wall affect the strength of the attraction? What are the governing equations at play? I am trying to gain insight as to why or why not the...
  33. H

    Is MFE a good way to go into Wall Street

    I read many career advices,but some problem confuse me.I hope someone could help me. Thanks in advance. 1)I am Chinese,many friends around me believe that get MFE in US degree will help them to go into Wall Street.Is it right?How many people around you have MFE degree? 2)Most of the...
  34. D

    Force exerted on the wall of a container.

    I am doing a question about oxygen in a cubical container, and am being asked to find the average force a molecule exerts on one of the walls of the container. I know the force is equal (in magnitude) to the rate of change of momentum of the molecule, but how can I know the duration of the...
  35. C

    Gravity retaining wall with back slope and cohesive soil

    Homework Statement I have a gravity retaining wall with a backslope and an inlcined prestressed anchor. The soil properties are c'=5 kPa, phi`=15 degrees, gamma=16 kN/m3. The water table is well below the bottom of the retaining wall. I have been told to assume the wall adhesion is 80% of...
  36. A

    How to support a sign on our museum wall?

    Hi all, I went to an engineering school 40 years ago but never finished, so I kind of know that this is easily solveable. I have a triangular sign 12' long (attached to wall) that is 2 1/2' thick and sticks out from the wall 6'. If I use 2 guy wires anchored to the wall 12' apart, that...
  37. M

    Ideal gas: total kinetic energy of molecules striking a vessel's wall

    Molecules in an ideal gas contained in a vessel are striking the vessels wall. I am trying to find the total kinetic energy of gas molecules striking a unit area of that well per unit time. The number of collisions per unit area per unit time is derived from the normalized Maxwellian...
  38. edward

    What caused the financial crisis on Wall Street?

    From PBS Frontline: http://www.pbs.org/wgbh/pages/frontline/money-power-wall-street/ The first two parts of the most recent and informative documentary on Wall Street and the financial crisis. The next two air next Tuesday. Frontline spills the beans and opens several cans of worms...
  39. R

    Converting a toy that runs on batteries to wall power

    In a desperate search to find a bubbly little icon for my aquarium, I came up disappointed and learned that nothing I grew up with was available anymore because it contained lead based paint. The disappointment quickly transformed into a challenge that got me excited. I was looking at a...
  40. I

    Retarded positions, extrapolation vs. hitting a wall

    I'm a compsci guy reading Feynmann's lectures leisurely. I find the retarded-field equations somewhat shocking due to the consequences of nature "extrapolating" trajectories to find the fields. Is my understanding of the following scenario correct? Let's say I have an "electrostatic compass"...
  41. A

    Inviscid flow around cylinder in presence of wall

    Hi there, Is there someone who would know how to solve the following potential flow theory problem: How to find the flow field and resulting force on a cylinder moving at a constant velocity through a stagnant fluid in the presence of a wall. The motion of the cylinder is parallel to the...
  42. Y

    Dynamics - Object Sliding Along A Frictionless Wall

    Homework Statement The 500lb box is released from rest in the position shown. The wall and ground are smooth. Determine (a) the angular acceleration of the box, and (b) the reactions at corners A and B at the instant after release. **G = center of mass **L = length of side = 2.5ft **phi =...
  43. A

    Engineering Seemed to hit a brick wall in Engineering

    Hello, I am a Junior Level Mechanical Engineer. It feels like I have hit a brick wall in my Engineering classes. I have a 2.75 cumulative gpa (major is 2.6). During my first two years I didnt have many problems in my classes. I finnished Calc 1,2,3 + DiffEqus (with a grade of B or better) and...
  44. M

    Momentums, Ladder against a wall force

    Homework Statement http://www.physics.ox.ac.uk/olympiad/Downloads/PastPapers/BPhO_PC_2008_QP.pdf Question 6 Homework Equations Moment = Force * Distance moved The Attempt at a Solution I have tried this and I am sorry to say that I have no idea how to work it out. I think it...
  45. D

    Calculating Velocity After Impact: What Went Wrong?

    Hello, i have the following questions. Let's assume that i throw a ball with mass 1kg and velocity 10 m/s at a wall with mass 100000000000000000 and velocity 0 using linear momentum i have in the beginning i have p = 1*10+ 100000000000000*0 = 10 after the impact the wall stays still...
  46. J

    Does the hup essentially represent the wall or curtain of the universe?

    does the hup essentially represent the "wall" or "curtain" of the universe? what i mean is, when you don't have any observable ability of what's going on behind a white curtain, if occurrences behind the curtain produce spots on the curtain which we see but we do no see their cause, we can only...
  47. U

    Ladder leaning against a wall friction factor

    Ladder of mass M and length L leans against a vertical wall. The friction factor between the ladder and ground is K. Calculate the minimum angle at which the ladder can stay in position without slipping off ignoring the friction between the wall and the ladder. Calculating momentum...
  48. O

    How to magnetize a concrete wall?

    As we know that concrete is an insulator, but if I apply extremely high voltage through this concrete at a certain level, the concrete's property may become semi-conductor. In this way, will it be possible to magnetize a concrete wall using an extremely high voltage in this way? Does anyone...
  49. A

    Why No Noise is Added to Sound Travel Through a Wall?

    We know that when sound travels through solids like a wall, the air molecules interact with solid molecules in porous medium to transmit the information hidden in sound wave.The question is that why no noise is added to someone's voice when we hear it from other side of a concrete wall ?
  50. M

    Determine temperature profile in cylinder wall

    I am conducting an experiment where I have a cylinder heated from the outside and a fluid flowing through the inside. I know the heat flux into the cylinder and I know the temperature at two points within the cylinder wall. However, I am not confident on the radial position of the temperature...
Back
Top