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)
Homework Statement
An automobile of mass 2000 kg is driven into
a brick wall in a safety test. The bumper
behaves like a Hooke’s-law spring. It has an
effective spring constant of 5 × 106 N/m, and
is observed to compress a distance of 1.67 cm
as the car is brought to rest.
What was the...
Although I do not remember the name of such question I am asking I am able to describe it in a sense. My Physics teacher had tried explaining and I was unable to conceive it, but maybe someone else can put it in laymen terms I suppose?
I walk against the ground applying 100 N (random amount)...
Homework Statement
An automobile of mass 3000 kg is driven into a brick wall in a safety test. The bumper behaves like a Hooke’s-law spring. It has an effective spring constant of 6 × 106 N/m, and is observed to compress a distance of 4.23 cm as the car is brought to rest. What was the...
Homework Statement
Golfer hits a ball with speed Vo at angle @ above the horizontal ground. angle is fixed and no air resistance what is min speed for which the ball will clear a wall of height h and distance d away. your solution will get you in trouble if angle @ is such that tan@ < h/d...
An architectural feature of a building is a flat wall that is angled out over the footpath. Measurements (in meters) of three vertices of the wall were recorded against the x,y and z axes:
x- axis is horizontal, the straight boundary of the footpath and the property on which the building sits...
Hi !
So recently I came across this interesting phenomenon that you can break through a strong concrete wall pretty easily by weakening it with certain holes drilled through it, following Hooke's law.
I had heard about it before, but have never really thought about it. But now that I am, I...
Hi PF,
I'm actually still an undergrad, so this is a long ways off, but I've been thinking about what possible route I want to take if/when I complete a Physics PhD program. I've come up with a couple reasons why the quant/finance path (or its analogue in 5-10 years) seems interesting to me...
Homework Statement
A space station in outer space has a total surface area of 580m^2 with emissivity of 0.62. The temperature of the outside surface is 156K. The walls are 0.25m thick with an average thermal conductivity of 0.038W/mK. Find the temperature of the inner wall of the space...
Hi.. I am just confused normal forces. The definition of normal force is always perpendicular to the surface. But when we draw a free body diagram for a ladder lying against the wall. The normal force is like slanted towards the wall. Please explain thanks.
Homework Statement
A 3.72 kg steel ball strikes a massive wall at 15.1 m/s at an angle of 58.6 with the plane of the wall. It bounces off with the same speed and angle. If the ball is in contact with the wall for .198s what is the average force exerted on the ball by the wall? Answer in...
HI
I would like to test the thermal conductivity of r wall by
K=Q*d/ A (t2-t1)
K =conductivity
d+=thickness
A= area
Q= heat flow
my problem how I could simulate heat in my experiment and how I will measure the heat flow?
could you please help me.
Kind regards
Homework Statement
[PLAIN]http://img571.imageshack.us/img571/4411/statics.jpg
A Man weighing 180lb has climbed 60% of the ladder shown. The ladder weighs 30 lb. Find the forces the wall & floor resists (reactions).
The angle the ladder makes with the floor is 60 degrees.
Homework Equations...
Homework Statement
A uniform 8 m 1500 kg beam is hinged to a wall and supported by a thin cable attached 2 m from the free end of the beam as shown in the figure. The beam is supported at an angle of 30 degrees above the horizontal.
a) free diagram
b) find the tension in the cable
c) how...
Hey just a question about the field, I understand most of the jobs are on wall street
if I'm a Canadian citizen is there any chance employers in the states would hire me, or is the paperwork too much? does it make a difference if i do grad school in the states? keep in mind I'm still in...
For a summer job I am employed to look into the use of composite paneling in place of sheet aluminum with stiffeners. I am suppose to find the required thickness of composite wall paneling in order to make a structure such as the one attached. Obviously it will depending on the material...
Mechanics problem: Ladder on a wall help please :(
Homework Statement
"A ladder of weight 200n and of length 5m rests with its lower end on a horizontal rough concrete surface and its upper end against a smooth wall. if the ladder just starts to slip when the angle between it and the concrete...
I was wondering what the changes would be if the a) the lung compliance decreased and b) the chest wall compliance decreased. Am i correct in thinking both would result in a fall in FRC, or would that only be for a fall in lung compliance? In addition, what would happen to other lung volumes...
Exterior commercial frames (.053") embedded in a concrete wall 8" thick with 3" layers of polystryrene (3# density) on each side of concrete cavity.
Frame rests on foam inside and outside of building. Frame is grouted solid with poured in place concrete.
Is there an appreciable (to be...
Homework Statement
Suppose that a ball is tossed at a wall; what is
the probability that it will tunnel through to
the other side? The mass of the ball is 0.14 kg,
the width of the wall is a = 0.2 m, and the one
who tossed the ball was deadly tired, so that
the ball is tossed only weakly at...
Hi everyone,
I have been on this forum since December last year. I have read many interesting threads by twofish-quants and many other members about the possibility of working in Wall Street after obtaining a Physics PhD. Although I understand that a career in Wall Street is really financial...
Homework Statement
A 100-N uniform ladder, 8.0m long, rests against a smooth vertical. The coefficient of static friction between ladder and floor is 0.40. What minimum angle can the ladder make with the floor before it slips?
The Attempt at a Solution
Not really sure where to start...
What is the definition of shear stress in a cylindrical tube? It seems like sometimes that is written
\tau = \mu \frac {\partial u} {\partial r}
but then at some magic moment it gets rewritten as
\tau = - \mu \frac {\partial u} {\partial r}
so as to arrive at formula like
\tau = -...
Please help:
I need help to figure out the following:
Given:
An alluminum wall of thickness s.
T outside wall, To
T inside wall, Ti
If the temperature changes on one side of the wall To, how long will it take until the the other side of the wall Ti reaches Tr, where To < Tr <Ti
I...
Homework Statement
A metal plate (with mass = 7kg and Length = 1.6m) is leaning against a frictionless wall and made an angle (Phi). The foot of the plate is made of circular edge that is situated at a V-grooved gap with angle (Theta). There are three normal force: F(wall) for the normal force...
A mass retaining wall having a vertical rear face is 0.4 m thick at the top and 0.8m thick at the base, is1.6m high and made of concrete of specific weight 24kN/m3. It holds back Earth with a specific weight of 18kN/m3 and an angle of internal friction of 20˚. The coefficient of friction...
Homework Statement
Gas is contained in an enclosure in which one of the walls is a plane of area A. The wall
acts as a frictionless piston, moving with constant velocity u in the positive x-direction,
thus increasing the volume V of gas enclosed.
A gas molecule of mass m approaches the...
Hello all, I came across what I think is a very interesting question the other day;
How would you treat a particle trapped in a square well that had one finite wall and one infinite wall? Say for E[SUB]n[SUB]~(n*pi*(h-bar))2/(2m(L+2d)2) would you replace the 2d by 1d? As you can only find the...
Using a slingshot, the boy fires the 0.3 lb marble at the concrete wall, striking it at point B.
If the coefficient of restitution between the marble and the wall is e= 0.6, determine the magnitude of the speed of the marble after it rebounds from the wall.
initial velocity is 75 ft/s...
Homework Statement
A uniform ladder 5.1 m long rests against a frictionless, vertical wall with its lower end 3.1 m from the wall. The ladder weighs 165 N. The coefficient of static friction between the foot of the ladder and the ground is 0.39 . A painter weighing 739 N climbs slowly up...
Homework Statement
a uniform 2kg horizontal beam is 50cm long is bolted to a wall and supports a 5kg sign. calculate the tourqe produced by the combined weight of the beam and the sign about where it is mounted to the wall.
Homework Equations
tourqe = F x Perpendicular distance
The...
I have computed the flow past a golfball and I am trying to calculate the shear stress on the surface of the golfball but I am having trouble figuring out how the wall shear stress is defined on 3D complex surfaces.
When I am on the main part of the golfball that it is similar to that of the...
Homework Statement
Suppose I throw a ball at a wall parallel to its x-axis.
At the moment it hits the wall, what forces are acting upon the ball?
Homework Equations
None. Relevant assumptions: ignore any spin on ball.
The Attempt at a Solution
I think they'll be:
-...
Homework Statement
A bus is moving at 37.00m/s towards a wall. The sound from the bus has an original wavelength of 0.1500m. The sound from the bus reflects off the wall. What frequency sound does an observer on the moving bus hear from the reflection??
Homework Equations
Moving Observer: fo...
I've seen this exact question in a book.
(This is not homework)
I've always thought this is because work has nothing to do with effort,
but seeing this question on a book quite shocked me actually, is there any deeper explanation?
Hey there, I'm pretty new to physics and need to learn how to calculate the U-value for a wall.
I do have an assignment to do with this but won't post that here as I'd rather learn to do it myself but could someone please post some sort of example of finding U-value using a brick wall with a...
My friend and I have been discussing this for days only to discover we're completely ignorant of the forces involved:
If I hit a golf ball at a brick wall that's, say, 5 feet away, will the golf ball take more damage from the wall, or from the club?
Please, help me settle this lest I lose...
This Is really simple I just can't remember what way Sin and Cosine go
Homework Statement
Here is the problem:
7 (b) A uniform ladder rests on rough
horizontal ground and leans against
a smooth vertical wall.
The length of the ladder is 5 m and
its weight is 80 N.
The angle between...
Basically I don't know where to even start. Does anyone know a good page that explains this topic? I would be very grateful if someone could provide a solution, but I know that's too much to ask. Thank you very much for your time.
Homework Statement
The plane region defined by \[A = \left\{ {(x,y)/0 < x < 1,0 < y < \infty } \right\}\] defines the profile of a semi infinite wall, where there's a stationary regime heat flow. The left and right sides are isolated at 15º, and the base is isolated at 0º. Find T(x,y) in...
Assuming I have the same voltage, correct polarity, and sufficient current, can I generally replace any class 2 power supply with any other? This will be used for common household electronics. In particular, when researching power supplies, I see specifications for ripple, noise, setup, rise...
problem:
ladder is leaning against the wall.
There is friction between ladder and wall - f1
and there is friction between ladder and ground - f2
what is the minimal angle between ladder and ground that ladder doesn't fall down.
I though it's easy, but then i realized it's not only about...
Would anyone only help me to compare the impact or damage of a Futsal ball against a wall versus a basketball ball.
We have a new sport growing in popularity in the USA named Futsal. This sport is very popular worldwide and should soon become a Olympic Sport. In a few words, Futsal is soccer...
I am trying to calculate the force of a 2300 lb car hitting a wall at 40 mph. I know that momentum is mass x velocity and that force is mass x acceleration, but I'm not sure how they both relate to find the force on the brick wall.
Any ideas?
Homework Statement
A sheet of porous material is suspended in air at a distance of 1/4 wavelength in front of a rigid wall. For the frequency of interest, the mass of sheet is high enough not to move significantly under the influence of a sound wave. When a constant frequency plane wave is...
Homework Statement
A swimming pool has the dimensions 24 m multiplied by 9.0 m multiplied by 2.5 m.
(a) When it is filled with water, what is the force (resulting from the water alone) on the bottom, on the short sides, and on the long sides?
Homework Equations
F = P*A
P =...
A 10-ft chain weighs 24 lb and hangs from a ceiling. Find the work done in lifting the lower end of the chain to the ceiling so that it is level with the upper end.
since you just take a little piece and add them up through an integral
wouldnt it be the integral from 0 to 10 of 2.4x...
I am working on putting a new battery rack into a substation. I was re-reading the NESC and came across section 143. This section suggests it is not recommended to anchor my rack to both the floor and the wall. Can anyone explain why this is not recommended?
Hi physics folks-
Every year for the past 3 years, I have built an ice rink in my back yard. Unfortunately, I do not have the flattest back yard, in fact it has quite a downward slope and then a steep uphill slope. But, I'm determined the make the biggest rink I can reasonably make, given...
Lets say a hot object is at 500K and placed in a chamber with wall temperature of 300K. The surrounding air in the chamber is 320K.
So what is the mode of heat transfer for the hot objection? There is convection and radiation. so the heat transfer rate, q = q(conv) + q(rad), right...