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)

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  1. P

    Calculating Initial Velocity of Object Connected to Wall by Spring

    an object is connected to the wall through a spring and is resting at its equilibrium position. its mass is M and the coefficient of kinetic friction is 1/4. the object is flicked so that it will return to its original position (not instantly, but its oscillation is damped slowly). what is...
  2. S

    A ladder against a frictionless wall

    A uniform ladder of length 9 m leans against a frictionless vertical wall making an angle of 47° with the ground. The coefficient of static friction between the ladder and the ground is 0.41. If your mass is 74 kg and the ladder's mass is 33 kg, how far up the ladder can you climb before it...
  3. N

    Wall on the mexico/united states border

    Besides the cost, what is wrong with building a wall on the Mexico/America border? I don't see how this could be morally wrong, or wrong in any other way besides the cost of the thing.
  4. G

    A spinning ball hits a wall and bounces back question

    Hi, my question is this: A solid ball with mass M, radius R, speed U0, angular speed W0 hits a wall at the angle theta0. after the hit, the ball goes away with an angle theta1, angular speed W1 and speed U1. i'm asked to find the angular momentum for the point of hit, before and after the...
  5. P

    Throwing a tennis ball through a wall

    I was having an argument with my sister last night about the limits of scientific knowledge (her beliefs encompass a more "spiritual" world view than mine) and she brought up quantum mechanics as an example of how weird things are possible (as peddlers of hocus-pocus love doing). Leaving aside...
  6. Mk

    How can I build a blast wall using polycarbonate and tempered glass?

    What are blast walls made of? Something like plexiglass or something? How would I go about doing this? Something like on Mythbusters, I want to be able to see through it, while having some protection.
  7. Pengwuino

    This guy doesn't understand wall street

    http://famulus.msnbc.com/famulusgen/ap01-24-163025.asp?t=apnew&vts=12420061708 Microsoft's average daily volume is ~62 million. Microsoft's shares are up $0.02 in after-hours trading (when the news report came out) :smile: :smile: :smile:
  8. T

    Determine Wall Thickness for 1,000 in. Aluminum Tube to Support 10-kip Load

    An aluminum tube with an outside diameter of 1,000 in. will be used to support a 10-kip load. If the axial stress in the member must be limited to 30 ksi T or C, determine the wall thickness required for the tube. I used tau=shearing stress/area therefore 30(pie times 1-d)=10 but that is not...
  9. T

    What is the Minimum Velocity for a Rod Laying Against a Wall?

    does anybody know the rules to find minimum velocy in a rod laying against the wall with specific angle??
  10. M

    Disappearing and reappearing at the other side of the wall

    can anyone of u tell me is it possible by the present quantum state that we become pure energy at a position x and move to another location by the prpagation of energy as wave and reappear as particle at another location y
  11. A

    Calculate the force exerted by the wall on the ladder

    A 1.29-m long ladder weighing 200N rests against a vertical wall so that the top of the ladder is at a height of .590m. A 603-N man stands on the ladder at a distance of .390m along the ladder. Calculate the force exerted by the wall on the ladder. Assume that the wall is perfectly smooth...
  12. Cyrus

    New Wallpaper: My 2-Computer Network & 100Gig Maxtor HDD

    Just curious. This is my new wall paper. I got tired of my old one. I just bought a new Maxtor external hard drive that holds 100 gigs. I have two computers in my house networked, so I took ALL the files from both computers and put it on the external drive and made that drive on the network as...
  13. S

    Find the total outward force exerted on the vertical wall

    An above-ground backyard swimming pool is shaped like a large hockey puck, with a circular bottom and a vertical wall forming its perimeter. The diameter of the pool is 4.9 m and its depth is 1.3 m. Find the total outward force exerted on the vertical wall of the pool. so P= F / A and i used...
  14. S

    Possible for a torch to light up a wall

    Is it possible for a torch to light up a wall, but not reflect back to you so that you cannot in fact see the light hitting the wall? For instance I can see streetlights from a couple of miles away out of my bedroom window - therefore the light from the streetlights must be reaching me - but...
  15. N

    Red & White: Seeing the Wall Differently

    there is two rooms in one of them ,i lit a red bulb and in the other room a white bulb when I'm in the red room i see the wall that is between these two room,red,but when I'm in the room with white light i see this wall white. why?
  16. J

    Find Tension of Meter Stick Attached to Wall

    The problem states: a 0.13-kg meter stick is held perpendicular to a wall by a 2.5-m string going from the wall to the far end of the stick. (a) find the tension in the string; (b) if a shorter string is used, will its tension be greater than, less than, or the same as that found in part (a)...
  17. L

    A uniform board is leaning against a smooth vertical wall. Find torque

    A uniform board is leaning against a smooth vertical wall. The board is at an angle above the horizontal ground. The coefficient of static friction between the ground and the lower end of the board is 0.350. Find the smallest value for the angle , such that the lower end of the board does not...
  18. W

    The light year long wall

    Ok I have had a course is general relativity, but not on special. I was wondering something though... If you have a brick wall a light year long (when at rest) and then have it thrusted at you at a speed such that it is only 1ft long, i.e. .99999c, when would you be able to stand in front of...
  19. T

    A 5.0 kg block pushed 3 m up a vertical wall

    This 5.0 kg block is pushed 3.0 m up a vertical wall with constant speed by a constant force of magnitude F applied at an angle of theta = 30 degrees with the horizontal. mu kenetic = .30 between wall and block. I need to a). determine the work done by F, b) the force of gravity and c) the...
  20. E

    Load on ladder leaning against a wall

    Hello, I got this problem from a book "A light ladder leans against a perfetly smooth vertical wall at an angle of 30 degrees to the horizontal. A load of 800N is placed 3-quarters of the way up the ladder. If the ladder rests on a rough horizontal surface which prevents slipping, find the...
  21. S

    Fetal Heart Wall Velocity from Ultrasound Reflection

    A sound wave travels at a frequency 2.25 MHz through a pregnant woman's abdomen and is reflected from the fetal heart wall of her unborn baby. The heart wall is moving toward the sound receiver as the heart beats. The reflected sound is then mixed with the transmitted sound, and 87.0 beats per...
  22. D

    AC to DC Wall Adapter:Vout 12Vdc Measured 19.5V?

    On the adapter, Vout is 12Vdc but when I measured it with a voltmeter it shows 19.5V. Is there a typo or does the voltage somehow drops down to 12V when in use with a load?
  23. K

    Stuck on Physics Assignment: Finding Force Required to Move Block Up Wall

    Hi all, I'm in my first year of university physics (mechanics and waves) and am stuck on an assignment question. The question itself is not complicated, but I feel as though I'm skipping over something important. The question is: A 3.8 kg block is pressed against a vertical wall by a force...
  24. B

    Solving Retaining Wall Problem with No Math/Engineering Knowledge

    I know nothing about math/engineering, so I apologize if this isn't the proper place to post this question. Maybe I should be in a builder's forum or something. :confused: Anyways... I'm building a round retaining wall on a slope at the corner of my house. I'm using stackable bricks that...
  25. K

    Thermodynamics Question heat through a wall

    I'm stuck on this Thermo question dealing with heat transfer through a "plain wall" They give us the area of the transfer A = 1 m^2 They give us the thickness of the wall L = .2 m and they give us the rate of steady state energy transfer rate Qx = .15 kW They then ask, if the temperature...
  26. D

    Calculating Time Length of Train and Wall Intersection

    dont know how else to word the title but here's the problem: you are in a train traveling on a straight and flat track (just assume its going right to left for my explanation) at 3.0 m/s. your window is 0.9 m high by 2.0 m wide and as you look out, the wall is going up at a 12 degree slope...
  27. H

    Find the angle theta at which the ladder leaves the wall

    A uniform ladder of length L leans against a smooth (no friction) wall. The floor is also smooth (no friction) and the ladder makes an angle of Theta-0 with the floor when the ladder is installed at rest. a) Before the ladder leaves the wall, express the equations of motion of the ladder in...
  28. P

    Sliding ladder leaning against wall, and a triangle of maximum area

    Hello, Below are two questions i am unsure of. :rolleyes: Can someone please verify my answers and tell me if i am doing something wrong. thank-you for your help. :smile: 1. A rigid beam 30 m long is leaning against a vertical wall. If the bottom of the beam is pulled horizontally...
  29. 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...
  30. J

    So, the force on each wall of the box is 138 N.

    A cubic metal box with sides 32.0 cm contains air at a pressure of 1.00 atm and a temperature of 294 K. The box is sealed so that the volume is constant and it is heated to a temperature of 396K. Find the force on each wall of the box due to the increased pressure within the box. [The outside...
  31. N

    Ladder against a wall how simple

    OK, so this appears to be a very simple problem... but I can't seem to find the way to do it... Anyway the problem is: A uniform 6.74 m long ladder of mass 15.6 kg leans against a smooth wall (so the force exerted by the wall, FW, is perpendicular to the wall). The ladder makes an angle =...
  32. U

    Ladder resting against wall - find forces

    A 15m ladder weighing 500N rests against a frictionless wall. The ladder makes a 60 degree angle with the horizontal. I need to find the horizontal and vertical force that the ground exerts on the base of the ladder when an 800N firefighter is 4m from the bottom. the total mg down is 1300N. I...
  33. Math Is Hard

    Soundproofing an Office Wall: A How-To Guide

    The wall behind me in my office is about 10 feet across and about 12 feet high. The top part of it consists of a window panel that is about 10 feet across x 4 feet high. There doesn't seem to be any insulation in the wall and it doesn't block the sound very well (well, almost not at all) coming...
  34. D

    Reach the End of Universe: Is There a Wall?

    If u reach the end of the universe, do u think there's a wall? All thing must have an end right?
  35. N

    What is the purpose of thin-walled cells?

    Cells with thick wall can support the whole organisms. Then what is the function of thin wall?
  36. R

    Mastering Physics: Ball hits wall Elastically

    First off let me say I am completely stumped. I don't remember teacher teaching this, and its definitely not in book(I went through it 3 or 4 times) and its not even the same book mastering physics uses... The Question is : What is the final angle that the ball's velocity vector makes with...
  37. B

    How Much Force Did Jean Valjean Need to Climb the Walls in Les Miserables?

    In Victor Hugo's Les Miserables, the main character Jean Valjean, an escaped prisoner, was noted for his ability to climb up the corner formed by the intersection of two vertical perpendicular walls. Find the minimum force with which he had to push the walls (assume both hands are to exert the...
  38. T

    How Is the Average Force Calculated in an Elastic Collision with a Wall?

    I'm stumped on this question: A ball of mass m moving with velocity v_i strikes a vertical wall. The angle between the ball's initial velocity vector and the wall is theta_i as shown on the diagram. The duration of the collision between the ball and the wall is delta t, and this collision is...
  39. U

    Pushing against fabric vs wall

    If a piece of fabric was stretched out, and I pushed my finger into the fabric with a force of 5N, the fabric will push back the 5N because of its potential energy. correct? So what if I did the the same thing and pushed my finger agaist a wall? The wall doesn't stretch but it still pushs...
  40. E

    A car crashes into a concrete wall

    Here it is: A 2000-kg car traveling at 85.0 km/h crashes into a concrete wall that does not give at all. Estimate the time of the collision, assuming that the center of the car travels halfway to the wall with constant deceleration. (Use 5.75 m for the length of the car.) I know I need to...
  41. I

    Block sliding on vertical wall

    Can someone please help me with this problem? I've tried a few different things but none of them worked... The weight of the block in the drawing is 99.0 N. The coefficient of static friction between the block and the vertical wall is 0.510. (a) What minimum force F is required to prevent...
  42. S

    Solving "6. [SFHS99 5.P.60.]" Physics Problem

    Hey everyone, my first post here, hope it's ok that it's a question... I've got this physics problem that is absolutely stumping me, is abnormal from all the other forces problems I've done before, and uk is throwing me for a loop too...here it is: 6. [SFHS99 5.P.60.] A 5.5 kg block is...
  43. P

    Probablity of Walking through a Wall

    Apparently, if all your particles are primed for tunnelling through a wall then you can walk through it, but the probability of all your particles tunnelling simultaneously is so low that you would have to attempt it more times than the age of the universe in years. Could someone please explain...
  44. kat

    News Hypocrit EU builds Apartheid Wall

    http://worldnetdaily.com/news/printer-friendly.asp?ARTICLE_ID=39998
  45. wolram

    Switch off my PC at the wall socket and reboot

    Help, I have to switch off my PC at the wall socket and reboot to get onto the internet , everything used to work OK. I have, SUSE 9.1, D link router and use Tiscali. Thanks.
  46. Shahil

    News Is the Israel Wall a symbol of oppression?

    http://www.news24.com/News24/World/News/0,,2-10-1462_1560739,00.html What are your views on the wall? My view: It's been nicknamed the "Apartheid Wall" and it dwarfs the Berlin Wall. It's just a massive symbol of oppression which should not exist in todays's society. Why they were allowed...
  47. B

    News Woman raped while Husband chained to wall

    ((P.S: This post is not against American as nation, but it is good idea to hear news from different sources. I think the Video tape of this raping crime exist in the Pentagon after they show it in the Congress)) The US soldier held her by the hair to force her to look at her husband while he...
  48. V

    Should I Consider Momentum or Work Done in Calculating Car Collision Damage?

    I am trying to find the kinematics of a car collision with a wall. To calculate the damages, should I take into account the momentum or work done? In other words, is this proportional to velocity or square of the velocity? Thanks, Venkatesh
  49. P

    China recognizes Great Wall myth

    Old news to most of us, but now China is officially recognizing it. http://www.cnn.com/2004/WORLD/asiapcf/03/12/china.great.wall.myth.ap/index.html Have the makers of Trivial Pursuit clued in yet?
  50. N

    What is the magnitue of the average Force from the wall stopping it?

    What am I doing wrong? Question: A 41 g bullet, with horizontal velocity of 496 m/s, stops 13cm within a soid wall. What is the magnitue of the average Force from the wall stopping it? This is how i tried to solve it Vi = 496, Vf=0, and Xf-Xi=.13m So Vf^2=Vi^2+2a(Xf-Xi) Which =...
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