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. Seydlitz

    Question about Centripetal Force (How it could make object glued to the wall.)

    Homework Statement A man standing inside a cylinder rotating with a particular angular velocity ω could take his feet off the ground and stay 'glued' to the wall of the cylinder. Draw the free body diagram of the man. The Attempt at a Solution My question is how the gravitational force...
  2. A

    Internal stress in a wall at object impact

    Homework Statement In the past months I've been working on a work calculating the behavior of a wall at an object impacting into it. I thought I have made it by knowing the impact force and the pressure it makes but then I realized that to fully complete my work I have to somehow calculate the...
  3. S

    Magnetism scenario: magnet attracted to iron wall

    Hi when a good former explained a theory, I didn't understand this very well. So I'll check it out again. Sorry for the many posts my me and thanks! When a magnet is placed vertically to an iron wall it gets attracted.(meaning the north and south poles are in contact with the iron wall)...
  4. H

    Is investment banking on Wall Street dead?

    Following the 2007 subprime mortgage crisis, I haven't seen any investment banks in the U.S. at all...as far as a career goes, is going into investment banking still a viable option for people in the maths/physics fields?
  5. C

    Shear valve Design. Wall thickness at break point.

    Hi. Situation: A pipe with a cut out so it will break when a shear force is exerted at the top of the pipe. The break point is at the cut out and the the force is impact in lbs. What is the wall thickness(or cross sectional area) at the cut out point? I know i may be missing variables...
  6. K

    Heat transfer through wall - Insulation thickness

    Alright, chemistry student here. No previous experience with these types of problems. Doing an interdisciplinary student project where we have to insulate a thin aluminum wall. http://i.imgur.com/8ztNq.gif We have a x=5mm thin aluminium wall used for dividing two air flows. T1=308 K and...
  7. S

    I was thinking about a rod colliding with an external wall, if you

    I was thinking about a rod colliding with an external wall, if you will, and began thinking what would happen if the collision was elastic (not sure if that is correct in this context, but simply the energy of the rod is the same before and after the collision.) I assume if a particle was normal...
  8. P

    A 5cm long, 30g lead bullet strikes a wall at 27°C and melts on the wa

    Homework Statement A 5cm long, 30g lead bullet strikes a wall at 27°C and melts on the wall without splatter. How fast was it going? What is the force on the wall? If the wall is made of 1kg of marble, what temperature will it reach? Homework Equations I don't know how to find the...
  9. W

    A book pressed against a wall, thought analysis.

    Consider that the book and the force applied by the hand is all together one part, so no worries if there is any slippage between the hand and the book. So then, the book is pressed against the wall with some force. The free-body diagram drawn in my head has a force of friction( μ static*normal...
  10. F

    The Doppler Effect - frequency of a bat reflected on wall

    The Doppler Effect -- frequency of a bat reflected on wall Homework Statement A bat flies toward a wall, emitting a steady sound with a frequency of 22.0 kHz. This bat hears its own sound plus the sound reflected by the wall. How fast should the bat fly to hear a beat frequency of 190...
  11. C

    Cylindrical Wall Heat Equation

    I'm a little bit rusty with my differential equations, and can't seem to see how solving for 1/r d/dr (r dT/dr)=0 has the solution T(r)=C_1*ln⁡(r)+C_2
  12. B

    Wireless Network Transmission Through Brick Wall

    Homework Statement A wireless computer network transmits data across the space between nodes as a modulation of a 2.45GHz (microwave) carrier signal. The signal is able to pass through a brick wall that is 100mm thick. Measurements have determined that the dielectric function at microwave...
  13. Y

    Physics Is a Physics Degree Relevant for Success on Wall Street?

    I have been contact by numerous people asking if a degree in Physics is useful on Wall Street. A lot of people have the miss-conception that you need a Finance degree. I know people with a communication degree and they are Senior and Executives on Wall Street. At the end of the day... 1. You...
  14. R

    Stagnation Point Heating - enthelpy at the wall

    Using the Fay-Riddell correlation, I can solve for the stagnation point heat transfer but I'm running into a snag. I'm doing this for a thermo-chemical equilibrium assumption. I'm confused with the enthalpy at the wall. I'm assuming a wall that is not adiabatic, but at some wall temp Tw. If I...
  15. QuarkCharmer

    Force of Bar on Wall: Calculating Inward Pressure

    Homework Statement How hard does the beam push inward on the wall? Homework Equations The Attempt at a Solution I know that the tension on the cable is 1.32*10^4 N From there I turned the weight and tension into x/y components and tried to add the x components, so that: 1.32*10^4cos(40) +...
  16. T

    HW help Finding the diameter of a hole punched in a wall.

    Homework Statement Like the title says, I have a homework problem that asks for the maximum diameter of a hole that can be punched into a sheet of polystryrene 6 mm thick, knowing that the force exerted by the punch is 45 kN and that a 55 MPa average shearing stress is required to cause the...
  17. mrspeedybob

    A block of cheese hits a steel wall

    ...at greater then the speed of sound in cheese. The leading molecules of cheese cannot transmit the force of impact backward because the speed of force propagation is limited by the speed of sound in cheese so the molecules must move either sideways or into the steel. If the steel is strong...
  18. C

    Fluids, pressure on a wall to determine max depth

    Homework Statement A square pool with 100-m-long sides is created in a concrete parking lot. The walls are concrete 90 cm thick and have a density of 2.5 g/cm3. The coefficient of static friction between the walls and the parking lot is 0.49. What is the maximum possible depth of the pool...
  19. M

    Imagine that you are looking at yourself in a mirror mounted on a wall

    Homework Statement Imagine that you are looking at yourself in a mirror mounted on a wall. From where you stand, you are able to see from the top of youre head down to the top of your shoulders. Suppose you were to back away from the mirror. Would the amount of your body that you see in the...
  20. S

    Superhero punching through a wall, breaking point of steel

    Homework Statement Comic-book superheroes are sometimes able to punch holes through steel walls. (a) If the ultimate shear strength of steel is taken to be 2.60X10^9 Pa, what force is required to punch through a steel plate 1.60 cm thick? Assume the superhero's fist has cross-sectional...
  21. R

    How Do You Calculate the Compression of a Ball Hitting a Wall?

    Homework Statement i) Find the average force exerted on a rubber ball mass m hitting a wall at speed v. The ball spends a time t in contact with the wall before bouncing off at speed v. ii) The change in KE of the ball from when it hits the wall to when it is instantaneously at rest iii)...
  22. H

    Coefficient of static friction between a ladder and a friction-less wall

    Homework Statement A uniform 7.7 m tall aluminum ladder is leaning against a friction-less vertical wall. The ladder has a weight of 291 N. The ladder slips when it makes a 59.0◦ angle with the horizontal floor. Determine the coefficient of static friction between the ladder and the floor...
  23. 5

    Probability of hand through a wall vs an electron

    a friend and I were trying to see if it would be more probable to put your hand through a solid wall, or for an electron to be 1m away from the nucleus (consider the electron is the only particle around). would this even be possible to calculate? what would we do? thanks!
  24. S

    Does 1 car hitting a wall at 120mph = 2 cars colliding, each going 60mph?

    I've been searching around the internet and there doesn't seem to be a straight answer for this. People just spit out an answer and don't back it up with any explanation. This is a complex situation in real life, so let's assume both cars are of the same mass and simplify the scenario by...
  25. A

    Shear stress on oscillating wall in viscous incompressible fluid

    Homework Statement A layer of viscous incompressible fluid of thickness H lies on top of a solid wall that oscillates simple harmonically w/ angular frequency Ω. u(wall)=Acos(Ωt). Ignore the motion of air above the fluid layer and find the shear stress at the wall. (Shear stress on free...
  26. N

    Impact of a cannonball on a brick wall

    If you had a cannonball made that was 5 pounds in weight and it hit a brick wall at a speed of 1,000 miles per second at the point of impact, how many pounds of pressure per square inch would the cannonball exert on the brick wall?
  27. T

    Finding the pushing force needed to keep object from sliding down wall

    This problem has been bugging me, seeing that my answer seems off. But who knows. Given the following measurements, find the required pushing force needed to keep a book from sliding down the wall. Homework Statement M= 2.88kg Coefficient of static friction= .322Homework Equations Seeing that...
  28. A

    Block Pushed Up a Vertical Wall

    Homework Statement What force is needed to move a 10 pound block up a vertical wall at a constant speed by pushing at an angle of 53 degrees with the vertical? Mu=0.3 At what minimum angle with the vertical would you be unable to push the block at all regardless of how large the force...
  29. A

    Momentum of ball bouncing off wall

    Homework Statement A racquet ball with mass m = 0.247 kg is moving toward the wall at v = 12.4 m/s and at an angle of θ = 32° with respect to the horizontal. The ball makes a perfectly elastic collision with the solid, frictionless wall and rebounds at the same angle with respect to the...
  30. X

    Ladder against wall. (If you help me, you are a legend).

    Homework Statement A uniform ladder AB, of weight W and length 2.5m rests against a smooth vertical wall OA with its foot on smooth horizontal ground OB. The ladder is in a vertical plane perpendicular to the wall. It is kept in position with OA=2m and OB=1.5m by a light rope OC joining O to...
  31. I

    Calculating Ball Velocity: Cricketer to Wall

    Homework Statement The distance from the Cricketer to the wall is 70 metres across level ground. The ball reaches its maximum height of 30 metres as it passes directly above the wall Both the height and the distance to the wall are measured from the point at which the ball is hit by the...
  32. M

    Breit Frame of reference ( Brick Wall )

    Breit Frame of reference ("Brick Wall") I am having a lot of trouble understanding breit frame of reference.I was trying to solve griffiths problem 3.21 (1st ed.): Consider elastic scattering- A+B----->A+B If particle A carries energy E, and scatters at an angle theta in the CM, a) what is...
  33. C

    How Does Airflow Through a Porous Wall Depend on Temperature Gradient?

    Homework Statement What we know is that we have two impermeable walls with a porous material inside (the porous material gives a simply restraining force proportional to the movement itself). we have a stationaly flow, so that dw/dt=du/dt=0. u and w are the velocities in the x (horizontal)...
  34. E

    Projectile Motion cannonball fired on top of a wall.

    Homework Statement A knight fires a cannon ball from the top of the castle wall. the cannonball is fired at a speed of 55 m/s and an angle of 27 degrees above horizontal. A cannon ball is accidentally dropped and hits the moat below in 1.4s. how far from the wall does the cannon ball hit...
  35. K

    How Much Force Can Tip a 16' Tall Theatrical Wall Packed with Lights?

    Hello, I am a college student getting my degree in technical theatre. I will be the Technical Director for our production of Altar Boyz. The designer has designed a wall of one inch box tube. the wall is 16' tall by 32'9" wide. It has an open framing and the lighting designer has decided...
  36. W

    Difficult Ladder Against Wall Torque Problem

    Difficult Ladder Against Wall Torque Problem! Homework Statement An 85 kg person stands on a uniform 6.6 kg ladder that is 3.9 m long, as shown. The floor is rough; hence it exerts both a normal force, f1, and a frictional force, f2, on the ladder. The wall, on the other hand, is...
  37. C

    Wall Acceleration: Physics Noob's Curious Query

    I'm a bit of a physics noob, but I am always curious about everything in the world. I concluded from Newton's third law that when you exert a force on a wall it exerts a force back on you. But I want to know from where does that force actually come? I mean ok you as a person might have a...
  38. V

    News Occupy Wall Street protest in New-York

    New-York is in second week of Occupy Wall Street protests. Around 5,000 Americans came to Wall Street on September 17. Occupation continues till now, although new-york times reports arrests of 80 people. http://www.msnbc.msn.com/id/44656667/ns/us_news-life/#.Tn-17tSfTks...
  39. T

    Hit a wall with Analysis, also with a problem in Linear Algebra

    Homework Statement prove that if 0<a<b, then a < \sqrt{ab} < (a+b)/2 < b Notice that the inequality \sqrt{ab} \leq (a+b)/2 holds for all a,b \geq 0. ------------------------------- the linear algebra problem is Let V be the set of pairs (x,Y) of real numbers and define a modified...
  40. A

    Simple Beam , Gravity Wall And Column

    Homework Statement Homework Equations The Attempt at a Solution Hi from Turkey...I really need to solve this 3 problem...I will enter exam whit same problems...I have some attempt but i really need to exatly result...Because our teacher doesn't give mark your solving way...So...
  41. B

    Heat Transfer Through a Plane Wall

    Homework Statement Consider a large plane wall of thickness L = 0.4m, thermal conductivity k = 1.8W/(m*K), and surface area A = 30m2. The left side of the wall is maintained at a constant temperature of T1 = 90 C while the right side looses heat by convection to the surrounding air at Ts = 25...
  42. E

    Solving Forces on Ladder: Wall & Floor

    A uniform ladder of mass m = 30.0 kg and length l = 2.50 m leans against a frictionless vertical wall. The ladder forms an angle theta = 75.0 degrees with the rough floor. The coefficient of static friction μ between the floor and the ladder is equal to 0.288. Determine the force Fw exerted on...
  43. M

    You've hit a wall, hard and you're miserable

    What do you do when that happens? You're fully motivated to study what you have to, then it turns out that you just can't seem to grasp certain concepts. Either it's because you're tired. Or you simply can't *see* it right and you just don't get what's going on and it makes you miserable. What...
  44. jtbell

    50th Anniversary of the Berlin Wall

    Germany marks 50 years since Berlin Wall (BBC) I was seven years old at the time, so the Berlin Wall was part of my image of Germany as I grew up. In 1972 while I was in college, I visited Germany and got to see the Wall for myself:
  45. R

    Ladder against a frictionless wall

    A uniform ladder leans safely against a vertical wall at an angle 45° to the horizontal ground. The wall is 100% slippery, while at the ground the coefficient of friction is µ . Prove that since the ladder is not falling, µ \geq 0.5 I've attempted to solve this, and think I have...
  46. O

    Tricky problem: Falling plank originally leaning against a wall

    Homework Statement A plank of lengt 2l leans against a wall. It starts to slip downward without friction. Show that the top of the plank loses contact with the wall when it is at two-thirds of its initial height. Hint: Only a single variable is needed to describe the system. Note the motion...
  47. Y

    Is the electron's energy changed when the infinite potential wall moves?

    we know the electron's energy in the the infinite potential walls whose distance is L. If the infinite potential wall moves suddenly, will the electron's energy be changed?
  48. D

    Will I hit an intellectual wall with math?

    Will I hit an "intellectual wall" with math? Every so briefly, for one semester, I was a math major in college. I got lazy and wussed out and graduated with a liberal arts degree. 7 years later I'm feeling pretty dissatisfied with my career and long term job prospects. Seems like...
  49. M

    Physics Physics, Maths & Philosophy: Wall Street Prospects

    Hello I am currently thinking about uni options for next year. I am very geared towards physics, maths and philosophy. Through my many searches on the internet I stumbled upon the idea of getting a PhD and working on Wall Street. This idea grabbed my interest as one of my hobbies has been...
  50. L

    The dynamic heat transfer in tube wall

    When I read some heat transfer book, I got a problem. There are some numerical calculation methods in dynamic heat conducting in tube wall, but all the methods assume the temperature on one side of the tube and then calculate the temperature distributed in the wall. But are there some methods...
Back
Top