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. LCSphysicist

    Succesive collisions between a ball and a wall

    Ignore the letter a. See b. I disagree with the variation of the velocity. To me, that need to be 2(Vo+V) " My point is that initial velocity before striking the wall was Vo towards the left and after the collision, the velocity is Vo + 2V towards the right, thus making the change of velocity...
  2. A

    Misc. Calculating load/force for an adjustable climbing wall

    The construction of this climbing wall is all done with 2x6 boards and 3/4" plywood. With some base calculation I estimate the wall to weigh roughly 400 lbs. Assuming the max weight of a climber is 200lbs. That would put me at 600lbs. Since this wall is on a hinge the maximum weight at the top...
  3. S

    Pushing a book against a wall and keeping it up

    The answers show that the static friction between the book and the wall points in the same direction as the vertical component of the applied force. That is, Fsin(θ) + ForceFriction -Mg=0. But why does the friction point in the same direction as the vertical component of F? More generally, if...
  4. C

    Graphing a spring mass collision with a wall

    Hi, I'm looking for help making a graph/model for evaluating the "bounce" of a mass behind a spring that collides with a wall. The setup would include one simple spring mass system that is attached to a wall, and another wall which is closer to the mass than the spring's free length. The mass is...
  5. D

    Calculating the wall thickness of a vacuum chamber

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  6. domingoleung

    Simple Mechanics Problem -- Block connected to a wall by a rope

    (So this is the system given) The following is my analysis: (i) (ii) Well, my problem is - I got a negative acceleration and its quite impossible to have block B moving to the left. So I am wondering if there are any mistakes I've made.
  7. C

    Engineering Where does the bending moment exerted by a wall on a beam come from?

    M = r x F r = 0 ∴ M = 0 But this is clearly wrong. For some reason, the "reaction moment" must exist. Why? Where does it come from? More specifically, which force(s) produces the bending moment, and at what distance(s)? Does it come from the reaction force form the wall on the left end of the...
  8. gbriggs

    LaTeX Exploring Alternatives for Thinnest Latex Tube Wall Design and Inflation Methods

    1/8" ID X 1/64" wall latex tube?
  9. B

    Finding the angle between a wall and a broken rope

    I tried to work out the solution using h. I get a trapezium, but there is always a lack of additional information. I looked up the solution and BAM, there is this simple equation for sinα. I really don't understand how do we get such a solution. I leaned you can use trigonometric functions in a...
  10. Amik

    Conservation of momentum when a ball hits a wall

    I think we can.Although the wall is not moving, it is just because the wall has a huge mass.As rhe law of the conservation of momentum states(suppose the ball hits the wall from the left), when the momentum decrease by J, the momentum of the wall increase by J, which means the momentum of the...
  11. A

    Force of the Ladder on a Wall Torque

    I've been working on this problem for a couple days now and I'm clearly missing something. I first went ahead and solved the triangle. Hypotenuse is 5, height is 4, the last side is 3 and the angle is 53 degrees. I went ahead and did the sum of forces in the y direction = Fn - Fbucket - Fearth =...
  12. A

    What materials are used for the tokamak toroid wall?

    There are two questions that arose in my mind, first of all tokamaks use toroidal field coils which create a toroidal field within the torus to shape the plasma and confine it, but here is a question, the toroid coils have a static B field produced from a DC current in them, what kind of metal...
  13. O

    Comp Sci How Is the Rebound Distance of a Ball Calculated After Impact?

    My attempts involved using suvat equations to determine the rebound distance : S = 0.5 * (u + v)*t With u being 50 and v being 0 t being time taken to fall down (Height of impact / gravitational acceleration) t = 48.41 / 9.81 Plugging the numbers in gives S = 123.365m This is where i get...
  14. maistral

    Boundary conditions for convective heat and mass transfer + wall Temperature

    I am operating via finite differences. Say for example, I have this pipe that contains a fluid. I have the boundary condition at x = x1: k is the effective thermal conductivity of the fluid, T is the temperature of the fluid at any point x, hw is the wall heat transfer coefficient, and Tw is...
  15. Kaushik

    Find the force acting per unit width on the vertical wall

    A container of height 3m and width 5m is filled with water upto 2 m. It is accelerated such that the water is at the brim (it is about to spill). When it moves with this acceleration find the force acting per unit width on the vertical wall. I found the acceleration for the condition provided...
  16. Santilopez10

    Sign Convention for Angular Acceleration in Rotational Motion

    we know that the center of instantaneous 0 velocity lies in the interception of 2 perpendicular lines to 2 points, which in this case lies above B. The velocity of any point of the rod can be described relative to the center of instantaneuous 0 velocity ##(Q)## as: $$\vec v_{P/Q}=\vec \omega...
  17. brotherbobby

    How Does Braking Compare to Turning in Avoiding Collisions?

    1. For the car to apply brakes, we have ##v^2=2ar⇒a=\frac{v^2}{2r}=μg\;\;[ma=μmg]⇒v=\sqrt{2μgr} ## 2. For the car to go in a circle ##\frac{mv^2}{r}=μmg\Rightarrow v=\sqrt{\mu gr}##. We find from above that the maximum velocity ##v## possible to avoid a collision is ##\sqrt{2}## times as much...
  18. Like Tony Stark

    Is the Normal Force on m2 Affected by Vertical Acceleration in Different Cases?

    I want you to tell me if I'm right For 1), does ##m_2## feel a normal force? Because I don't think so, since it isn't pushing the wall. For 2), ##m_2## suffers a normal force because it feels a pseudo-force to the left and so it pushes the wall
  19. Cerenkov

    B Can we observe anything beyond the CMB 'wall'?

    Hello. http://www.jb.man.ac.uk/distance/frontiers/cmb/node10.htm The above article refers to the CMB "wall" in sections 2.4.2 and 2.4.2.1. It's my current understanding that this wall prevents observation of the very early universe; i.e, earlier than 380,000 years after the Big Bang. I also...
  20. Old-Alien

    A string attached to a fixed wall and a mass on a spring

    Hi all. Multiple part problem that I'm really stuck on. I'll attach a file. At first I had attempted the whole problem with the idea that fixed wall was a fixed point, and that the mass on a spring was a "free" point. But I learned later that the mass can't be treated like a "free" point since...
  21. F

    I Why in the steady flow of a fluid, the fluid cannot move through the wall....?

    Because of temperature, molecules of fluid have chaos movements.So I do not understand why in steady flow,the molecules of fluid can not move through the wall of flow tube?I think two layers of fluid exchange molecules while they move.How do we understand when saying: fluid can not move through...
  22. T

    Subsea Pressure Housing Design – Wall Thickness for Stress & Buckling

    I’m designing a subsea sensor that will go to a max depth of 600 m (6 MPa/60 bar). In a simple model, it will be made of a pressure housing cylinder and two end caps, all grade 5 titanium. Some geometry is attached. I’m looking for advice on how to calculate the thickness of the...
  23. J

    B Getting a newspaper page to stick to a wall using wooden pencil

    Hi! Im trying out an experiment, where a newspaper page is supposed to stick to a wall using a wooden pencil, by rubbing the pencils long side on the newspaper page while its on the wall. But its not really working. I have checked the pencil, and there is no coating on it, just wood. It is...
  24. W

    I Dumbbell Sliding on Wall: Find Speed of Weights at Equal Velocity

    A dumbbell consisting of two weights of mass m and a bar connecting them of length L is sliding down a frictionless wall and floor, with one weight on the wall and one on the floor. The dumbbell starts sliding from rest. Find the speed of the two weights when they are equal in speed. I tried...
  25. DaveC426913

    How many spikes does it take to build a wall?

    When I first started this, I thought I'd need only one spike to stitch the 6x6s together and to fix it to the ground. But OK, I need two after all. Having finished two, I realized it's still not secure! How did I end up needing three spikes to stitch one section of wall? What did I do wrong??
  26. O

    Clearing a wall with a golf shot

    Every trajectory follows a parabola if we neglect air resistance. So we can calculate the maximum distance in x direction s_max. Also we can determine the time it takes to hit the ground again t_max. If the ground is everywhere the same height, I can assume that at t_max/2 the height (s_y) is at...
  27. P

    How to calculate the thickness of a wall of a dewar?

    Hello, i am trying to design a dewar for experiments at very low temperature. Unfortunately i do not know how to calculate the wall thickness. I can calculate the heat flow through the wall, but i do not know what to do further. Do someone know how to calcualte the thickness of the wall for a...
  28. Wrichik Basu

    What are these rusty metal pieces in my staircase walls?

    First, I am not an engineer, nor am I formally studying the subject. So, please pardon my ignorance. I recently found these in the walls of the staircase in our flat: The walls of the staircase had not been painted properly by the builder. Due to water seepage and damp, parts of the plaster...
  29. jedishrfu

    B We Need a Wall - Electrons are Crossing Our Borders

  30. S

    Static equilibrium -- A picture hanging on a wall

    Homework Statement https://imgur.com/v13K6sE a uniform rod of mass m is placed as shown, with one of its end resting on a smooth wall while 1/4 of the rod's length is sticking out of a rough table. Find the net force the table exert on the rod at the corner. Homework Equations i drew the free...
  31. S

    Phase difference between points on wall

    Homework Statement Parallel water waves of wavelength 10 m strike a straight sea wall. The wavefronts make an angle 30o with the wall. What is the difference in phases between the waves at two points 5 m apart along the wall? a. 30o b. 45o c. 90o d. 156o e. 180o Homework Equations Δφ = Δx / λ...
  32. S

    Temperature of a bar to produce certain force on wall

    Homework Statement A brass bar and a steel bar, each 0.8 m long are at a temperature of 20oC. Each bar is placed at that temperature between rigid walls 0.8 m apart. The cross - sectional areas for the brass and steel bars are 0.005 m2 and 0.003 m2, respectively. The coefficient of linear...
  33. S

    Why is the balloon sticking to the wall?

    When you negatively charge a balloon, by rubbing it on clothes, and then placing it against the wall, why doesn't the electrons move to the wall, causing the balloon to drop? I would have thought the electron transfers to the wall - therefore an example of conduction. Why is it induction and...
  34. S

    Projectile launched from an inclined plane strikes a wall horizontally

    Homework Statement There is an inclined plane which is inclined at an angle of 37° to the horizontal. A projectile is projected perpendicularly to the inclined plane at a velocity of 50m/s such that it strikes a wall kept at the foot of the inclined plane perpendicularly. Find the time taken...
  35. I

    How Does an Ideal Fluid's Velocity Change When Hitting a Vertical Board?

    Hi, I`m seeking for help in the following problem. A flat vertical board is traveling in water which is to be considered as ideal. One of its ends is in water, the other one is outside the water. Its velocity is v with respect to its normal. What is the velocity of the water stream directed up...
  36. mktsgm

    Hear Through Walls: How & Why?

    How and why do we hear through the brick walls? Does the sound actually penetrate the walls?
  37. M

    How to calculate rebound speed of ball hitting a wall?

    Homework Statement A ball of mass 0.075 is traveling horizontally with a speed of 2.20 m/s. It strikes a vertical wall and rebounds horizontally. Due to the collision with the wall, 20% of the ball's initial kinetic energy is dissipated. Show that the ball rebounds from the wall with a speed of...
  38. Alexanddros81

    A ball bounces off a brick wall, Find the average acceleration

    Homework Statement Serway Physics Section 2.4 Acceleration 14. A 50.0-g Super Ball traveling at 25.0 m/s bounces off a brick wall and rebounds at 22.0 m/s. A high-speed camera records this event. If the ball is in contact with the wall for 3.50 ms, what is the magnitude of the average...
  39. A

    How to calculate the refractory wall temperature?

    Homework Statement A gas-fired tube heater has the following data: Dimensions of the combustion chamber: 15 * 20 * 40 ft Tube outside diameter: 5 in Temperature of the tube=800° F Center to center spacing: 8 in Number of tubes (arranged in a single row of which 6 tubes are shield tubes) ...
  40. J

    A ladder against a wall problem

    Homework Statement A 70 kg window cleaner uses a 16 kg ladder that is 5.6 m long. He places one end on the ground 2.0 m from a wall, rests the upper end against a cracked window, and climbs the ladder. He is 3.5 m up along the ladder when the window breaks. Neglect friction between the ladder...
  41. sophia026

    Physics Homework -- block pressed against a wall is sliding....

    Hey! I've been trying to figure out these two problems but can't seem to get the right answer. Was wondering if someone could help me out? 1. A block is pressed against a vertical wall by a force F, as the drawing shows. This force can either push the block upward at a constant velocity or...
  42. F

    Structural query on removing a masonry wall and lintels

    My sister recently removed a structural wall in her ground floor apartment and I am very concerned about the workmanship. She trusted her builder to work out the size of the steel lintel which supports a masonry wall on the first floor above and above the first floor - is a standard pitched...
  43. S

    Pressure test containment wall thickness

    Hi If I know the velocity, mass and diameter of a missile from a failed pressure test how can I calculate the minimum thickness of a containment sheet steel wall say 1 meter away?
  44. J

    How to slow down a battery wall clock from the 1960's

    I have 2 new battery operated clocks that have been lying on the shelf for 50 years never used them both run after I oiled them, they have a motor that winds up a spring and the a little spring that goes around in circle one end fastened to shaft the outside end to a fixed point this rocks back...
  45. B

    Direction of The Force of a Wall Exerted on a Rod

    Homework Statement A rod is attached to a wall in such a way it can swivel. In this case: In which direction does the force (of the wall on the rod) point to? Here are two examples (see under attached files), but the the direction of the force is different. Why? Is maybe one of the pictures...
  46. Pedgepoke

    Ladder Leaning against wall -- find the coefficient of friction

    Homework Statement Ladder leans against wall at angle θ. It is L meters long and mass m. Find the coefficient of friction with the floor. Assume no friction at the top.[/B]Homework Equations ΣFx = 0 ΣFy = 0 Στ = 0 ƒ = μFn (Fn being the normal force with the ground) The Attempt at a Solution...
  47. J

    Banked Turns Part II: What Force Causes a Car to Creep up a Wall

    I wanted to dig deeper on previous question regarding Normal forces and banked turns vs. inclined planes. Intuitively, when a car going around a banked turn is going faster than the "tuned" speed (i.e., the speed at which no friction is required to keep it on the track), it will need friction...
  48. T

    Heat Transfer and Combustion -- A furnace wall consists of three layers of material

    Homework Statement A furnace wall consists of three layers of material as shown below. The thermal conductivities are: Firebrick = 1.15 W m–1 K–1 Insulating brick = 0.17 W m–1 K–1 Ordinary brick = 0.62 W m–1 K–1 Calculate: (i) the thermal resistance of each layer (ii) the heat loss per...
  49. T

    Heat Transfer and Combustion -- reheating furnace wall consists of 200 mm of firebrick

    Homework Statement A small reheating furnace wall consists of 200 mm of firebrick. The inner surface of the wall is at a temperature of 320 °C and the outside temperature is 35 °C. Calculate the rate at which heat is transferred, by conduction, through unit area of the wall. The thermal...
  50. I

    B Why does a wall break and not move when pushed?

    When there is a wall and a huge machine tried to move it and applied force on it at a point, why will the wall break at the spot the force is being applied and not move away?
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