# 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. ### Pressure vessel wall thickness ASME BPVC VIII vs AS1210

The ASME BPVC formula is t=PR/(SE-0.6P) where P = pressure , R = inside radius, S = allowed material design stress and E = joint efficiency factor. the AS1210 formula ,(equivalent nomenclature) is t=PR/(SE-P). This makes 1210 more conservative when using the inside radius . I suspect the pure...
2. ### Forces acting on a block that is pushed against a wall

Picture of problem: For the object to be moving, it must overcome friction. ##f=0.5*0.6F = 0.3F## ##mg=22N## Upward motion: ##0.8F>mg+f \rightarrow 0.5F>22 \rightarrow F>44N ## Downward motion: ##0.8F+f<mg \rightarrow 1.1F<22 \rightarrow F<20N ## I think correct option is D. Can you please...
3. ### B Collision time interval of a gas molecule with wall of container

I have been trying to make sense of the derivation of pressure under Kinetic Theory of Gases chapter, but it's not making sense to me when the impulse momentum equation is used for the collision between a gas molecule and the wall of the container. The book says that for the elastic collision...
4. ### I Wall material effect on Van der Waals gas?

Ref: Van der Waals Equation @ Wikipedia The above paragraph is explains how intermolecular attraction reduces the gas pressure, assuming that there is no attraction between walls and particles. In practice, would there be a change in pressure from one kind of wall to another, if we ensure...
5. ### I 1D Heat Transfer Analytical Wall

Hello everyone, I'm trying to solve the transient heat transfer problem within the ID wall. The material is steel, and it is isotropic. The properties are given below : L = 5 mm qin = 0 Tinf = 100 deg C Tini = 20 deg C rho = 7850 kg/m3 cp = 460 W/Kg.K k = 45.8 W/m.K h = 20 W/m^2.K alpha = k /...
6. ### Induction Heater at 50Hz or 60Hz from Kitchen Wall Outlet.

I'd like to make an Induction Heater design for Cooking purpose, where heat can reach up to 400-500F or so. I read in some other forums, that it's possible. So I'm trying to get more ideas and possibly learn how this can be done safely (in case I make it / if it's really safe). The Idea is use...
7. ### Calculating the energy savings of an insulated cavity in home wall construction

I am a client who bought a new house and the cavity in the wall was not insulated. I can calculate the U value of the uninsulated wall and the U Value of the wall if it were insulated correctly. front the two different U values I want to calculate how much extra energy is being lost through a...

27. ### Lab Experiment - Puck Impact on Wall, Analyzing Force

Please see attached image. This was a lab performed where a puck hit a wall shown on the page, the difficulty I’ve had is being able to see when and for how long the puck hit the wall as it is needed to find the average force in the system. Each dot on the page is 30milliseconds apart.
28. ### Pressure due to a Liquid on container Wall

I have just started this topic so i Don't have much clearity about it . In our school it was tought that Pavg = (Pi + Pf)/2 ...(i) If we have a cuboidal shape container then it should be pgh/2 ryt ? But also Pavg = Ftotal on the wall /A ...(ii) =...
29. ### Stick leaning on the wall, find the acceleration from the initial position

So the acceleration of point A was given by a force F exerted on cylinder that's along the direction of the stick, decomposed into the horizontal direction. so aA = F cos Θ The same force along the opposite direction is exerted on stick, and if we decompose that in vertical and horizontal...
30. ### I If I clap once to a wall, and then walk forward, will I hear an echo?

This is a diagram: ------------ reflective wall X --> Y I stand at position X and clap towards a reflective wall. Theoretically, could I walk to some point Y, where there is constructive interference between my clap and the reflected clap, resulting in my hearing a much louder sound. Is...
31. ### COVID Excellent Story On Breakthrough Cases From Wall St Journal

I get the Audio of the Wall St Journal every day. They had a surprising and excellent story on breakthrough cases. The bottom line is the US is seeing very few - even with Delta. The full story is behind a paywall, but non-subscribers can view some of it here...
32. ### Alonso and Finn Volume 1 Chapter 4 -- A sphere is held against a wall by an inclined plane

I’m pretty sure that the force on the sphere by the wall and plane has to equal mg so the sum of the normal force is steered by the wall and plane has to equal mg. I’m not sure where to go after this. Is mg the answer or is there something I’m missing?Here is Fig: 4-31:
33. ### Time of Impact of Gas Molecules on the Inner Wall of a Pressure Vessel

In derivation of relation for pressure of Gas ,(see pic below) the time for rate of change of momentum of molecules should be the time for which the wall of the vessel and the molecules kept interacting with each other, not the time between successive collisions. As circumscribed below, my...
34. ### Rotating climbing wall - Components selection

Hello to all members! I'm looking for specific names of 3 mechanical components from the video: Component name 1: min 0:52 from the video Component name 2: min 1:01 from the video Component name 3 (the brake): min 3:53 from the video Perhaps anyone also has a link to the 3 components? I...
35. ### Force on two cables holding a liquid-filled container against a wall

Before, sorry for my English, it is not my native language I already have the solution to the issue, I just didn't understand a step. 1) Calculation of weight force (vertical): $$F_v = \frac{\rho \pi R^2 . L .g}{4}$$ 2) Calculation of force due to water pressure on the plate (horizontal)...
36. ### What are the forces exerted by a wall on a hinged rod?

I have a dilemma. If I look at the diagram and say the sum of the forces in x and y direction has to be zero, then I will simply conclude that the force of a wall on a revolvable rod is the blue N as drawn. But what if the force is actually the green N? To me, it makes more sense because if...
37. ### Motion of box on inclined plane connected by spring to a wall

a) When the system is in motion for the first time, the force causing ##M## to move is contact force with ##m## so: $$\Sigma F=M.a$$ $$N \sin \alpha=M.a$$ $$mg \cos \alpha \sin \alpha =M.a$$ $$a=\frac{mg \cos \alpha \sin \alpha}{M}$$ Is that correct? b) Is acceleration of ##m## the same as...
38. ### Wall made of Pendulum -- thought experiment

If your house wall is made of pendulum or a ball attached to a string on top. It won't attract seismic forces. Whereas if the wall is fixed solid. It can attract seismic forces. What is the physics explanation of it? Is it because you try to deflect momentum or inertia? What is the right...
39. ### A Obtain Normal Vector of Bubble Wall in Spacetime

So say I have a bubble embedded in a spacetime with metric: $$ds^2 = -dt^2 + a(t) ( dr^2 + r^2 d\Omega^2_2)$$ how do I compute the normal vector if I assume the wall of the bubble the metric represents follows a time-like trajectory, for any ##a(t)##? Since we are interested in dynamical...
40. ### Electrical Unconnected wall wart power consumption

Hi. Not homework. I left that behind me 40yrs ago:) How much power (if any) does a plugged in but unconnected wall wart (transformer/rectifier) consume? Eg. I have a phone charger labelled as: Input: 100-240V~50/60Hz 0.3A. ____________ Output: 5V - - - -...
41. ### Reddit Attacks Wall Street

Two weeks ago Gamestop was worth $20 a share. Today it's worth$350. As I just heard on CNBC: for the same money, you could by Gamestop or you could buy Delta. Why is this happening? Because a reddit sub saw that Wall Street was bearish on Gamestop and got annoyed. So in order to Stick it...
42. ### Building Overhead Hoist: Is 5"x5"x1/4" Wall Sufficient?

Hello, I am in the process of building an over head hoist in my shop.I've already taken delivery of the metal, so I hope I erred on the side of safety. I am spanning 20' and will be using a 1/2 ton electric hoist and trolly. I found a chart online from Harrington Crane Co. That specified that a...
43. ### What happens when the maximum is exceeded in the Mass-Spring System?

If M is displaced by an amount + x from equilibrium.What happens to the two masses at the point of release for displacements of x and less? Will they remain static because mass m provides whatever it takes to stop mass M from moving till some x where m slips and M oscillates or Will they...
44. ### Acoustic reflections from an elliptical wall in Urbino city (Italy)

I was in Urbino a walled city in the Marche region of Italy. At the foot of Duke's palace we found an elliptical wall. It has been mentioned that the guards were once placed at the ends of the wall. In fact the city is located on top of a mountain, the guards had to watch over the whole valley...
45. ### Help please with a physics bet (2 cars colliding vs. 1 car hitting a wall)

so the question is this. 2 cars with the same mass hits each other at the speed of 30 miles. at which speed a car needs to hit a wall in order to get set same impect? i don't care what Will hurt the driver more. thanks!
46. ### Wall to wall airfoil in a wind tunnel

Does wall to wall airfoil produce downwash in wind tunnel ?
47. ### Understanding Stress in Pipe Walls: Impact of Internal Air Pressure

Consider a pipe. The pipe is not crushed by the air pressure because the same air pressure is acting from inside the pipe. But this means that the material of the pipe is being compressed on both sides by some air pressure. So is it correct to say that the through-thickness stress in the pipe...
48. ### B Dropsheet-duct tape wall in The Martian

While not managing to sleep, I was trying to calculate how deep a pool of water would be to simulate Watney's pressure wall holding in the Hab atmo. Let's say, generously, the air pressure in the Hab was a mere 0.5 atmos. That's .51kg/cm^2. Mars is .02 atmos, so effectively vacuum. We can...
49. ### Why does a car apply a force to a wall?

when we have 0 acceleration(constant speed) like a car traveling at a constant speed, ƒnet=ma ƒnet=(mobject+mfriction).(aobject+afriction) let m object be 1500 kg. m friction be 10 kg a object be 0 a friction be 20m/s^2 so when we calculate fnet=-20*1600=-32 000 Newtons. which means wall applies...
50. ### Electric field produced by a uniform charge density on a wall

I couldn't solve the question. Can you help me?