Wall Definition and 756 Threads

1. Homework Statement I have already solved this one weeks ago, and i have a test Tuesday so i was reviewing these problems. I understand everything when solving with 60N as the force.. but then when i changed the force to 20N, i had to use the coefficient of kinetic friction to get the correct...

After watching hours of those home improvement shows, you decide you want to paint you bedroom. You don't want to paint all four walls the same color (how boring!), but instead, you want to paint one wall a different color. The electric orange paint you've chosen for the "special" wall is more...

1. Homework Statement A block weighing 22 N is pushed against a vertical wall by a force of magnitude 60 N directed 30° above the horizontal. The block is intitally at rest. The coefficient of static friction between the wall and the block is 0.55 and the coefficient of kinetic friction between...

When sound hits a wall,part of it gets reflected and part of it gets transmitted due to acoustic impedance difference between solid and air. My problem,and point of this question is that having material or gas impedance number is completely useless unless we know the frequency and wall...

Does anyone know how to wall mount a shelf rack (similar to a Truss shelf rack) to a concrete basement wall and hook computer supplies (like speakers, monitors/displays) on them while making the shelf rack detachable at the same time?

The collision of a billiard ball against a wall is considered elastic. Intuitively i can accept it. But analytically i don't understand it. Why does the wall not take any relevant amount of energy from the ball? Is it connected to the change in temperature of the wall ? What scenarios can we...

Hi everyone, Our professor gave us a bunch of solved problems to practice with before the exam, and this one I'm struggling with: I'm trying to work through the solution step by step, and I get stuck at the point (3). What I understand is that we want to get the value of RH, which is...

Homework Statement A circular plate with radius 0.5 m and mas 5 kg is hung on the wall, fixed at a point that is 0.3 m above its center. The plate can freely rotate about the fixed point with no friction. A very short-duration impulse of 5Ns, along a direction that is tangential to the...

Homework Statement 1. On a long trip that you take to forget for a while about physics, you find yourself driving directly towards a canyon wall. You’ve previously noticed that your car horn has a frequency of 440 Hz. You glance at the speedometer and notice you’re moving at 30 km/h...

I have a doubt regarding the answer, a box separated by a movable wall has two compartments filled by a monotonic gas .Initially the volumes are equal but the pressure are 3P and P respectively .When the wall is allowed to move the final pressure is...

Homework Statement A 20 kg ladder rests against a smooth wall as shown. If a painter (50 kg) climbs 4.0 meters up a 6 meter long ladder, find the force, F1, the wall exerts on the ladder. The angle between the ladder and the ground is 53 deg. Homework Equations CW torque must = CCW torque The...

Homework Statement A 60 g tennis ball with an initial speed of 37m/s hits a wall and rebounds with the same speed. This collision lasts for two seconds. What is the maximum value of contact force during the collision? Homework Equations p=mv The Attempt at a Solution So I multiplied the mass...

I am looking at the wall-crossing formula for N=2 D=4 supersymmetry The Donaldson-Thomas "invariant" is supposedly given by \Omega = -\frac{1}{2} Tr (-1)^{(2J_3)} (2J_3)^2 + I don't understand how to use this formula. (By the way, the normalization is probably not the same for everyone so you...

Sounds wird but I tried it and people use this it help clime walls. How does this happen?

Homework Statement 'A small smooth sphere moves on a horizontal table and strikes an identical sphere lying at rest on the table at a distance d from a vertical wall, the impact being along the line of centres and perpendicular to the wall. Find the distance from the wall of the next impact...

Hi every body, I need help to calculate the pressure drop to double wall pipe with information as below, i understand need calculate pressure loss to the straight pipe, elbows and supports but I don't know exactly how. - Fluid : air - Double wall pipe (stainless steel) with outer pipe...

Hello, could someone explain to me, how I should cut a FeBa magnet, if it has one pole facing upward and the other downward so that the bloch wall would be across the entire length of the magnet. The dimensions of the magnet at hand are 152 x 102 x 52 mm. The bloch wall runs across the entire...

Homework Statement i know problems of this kind have been posted a lot but i have a few of my own questions please take a look at them thanks i am having several conceptual errors in rotational dynamics one of them is : since the rod is massless must there be net zero force and torque...

The Wall Street Journal is definitely interested in space debris - dead satellites, boosters, etc. - as they've run a number of stories on this topic over the past few years. E.g. Wikipedia has a link to a story from 2009 as one of the footnotes to their article on space debris, plus a web...

ok i read about that quantum mechanics article about how macroscopic objects have a extremely low probability of passing through a wall.Now i very clearly remember that 5-6 years back i have noticed my smiley sponge ball going into a place it cannot go to.Do you think it may have gone through...

Homework Statement Homework EquationsThe Attempt at a Solution When the plank leavs the wall at angle ##\theta ##, Torque about ground ## \tau _g = mgl \cos \theta = \frac { m(2l)^2 \alpha }3## Torque about COM ## \tau _c = Nl =\frac { m(2l)^2 \alpha } {12} ## Acceleration of COM: a =...

An elastic spherical ball of mass m and radius a moving with velocity v strikes a rigid surface at an angle θ to the normal. Assuming the ball skids while in contact with the surface, the tangential reaction force being a constant fraction μ of the normal reaction force, and assuming the...

Hey everybody. I just took a test where a problem described, "a ladder is leaning against a wall with an angle of A. It has a length L and it weighs mg. Assume no friction against the vertical wall and a frictional coefficient of B, find Ffriction" My dad, a quantum physicist, explained how the...

A smoker just moved into the mobile home next to the one I live in, and insists on smoking in his yard. I want to build a wall between us to block the smoke. I don't know how to calculate how high the wall needs to be, to keep the smoke from blowing into my yard. Can anyone help me to figure...

Homework Statement They ask for the smallest force P to apply if neither block is to slip. Coeff. of friction given as 0.25. The 20KG block is 196N; the 10KG block is 98.1N [/B]Homework EquationsThe Attempt at a Solution [/B] If we start at the 10KG block: Sum of forces x: N + cos26.6P –...

Homework Statement This problem is from "Fundamentals of aerodynamics" by John D. Anderson, Jr (Fifth edition, page 101): Consider a flat plate at zero angle of attack in a hypersonic flow at Mach 10 at standard sea level conditions. At a point 0.5 m downstream from the leading edge, the local...

Homework Statement The internal and external diameter of a hollow cylinder are measured with the help of a vernier calipers. Their values are (3.87 ± 0.01) cm and (4.23 ± 0.01) cm respectively. The thickness of the wall of the cylinder is ?Homework Equations Thickness of cylinder wall= 1/2...

I need to calculate the thickness needed for a retaining wall for a pond. The information I have is as follows: Depth of pond, area of pond, shear strength of retaining material, unconfined compressive strength of retaining material, length of retaining wall (will only be on one side of pond)...

Afternoon everyone, I just found this awesome site where I thought I could enlist the help of a lot smarter people than myself with my project. I want to build a garage elevator to raise and lower various articles from my storage loft. My loft has 9' floor with a 15' ceiling. I was going to...

Lets pretend there is a gun of some type that can fire electrons one at at time at a wall. The plane of the wall is oriented perpendicular to the x axis, which is to say that the wall is in the y-z plane some distance down the xaxis. There is no intervening screen with slits in it. We are just...

Homework Statement In this sketch, the mass m = 1.6 kg is pushed against a wall by force F, as shown, in the horizontal direction. The values of the coefficients of kinetic and static friction for the contact between are 0.81 and 0.84 respectively. The magnitude of F is slowly and continuously...

I have read an article talking about material research in fusion. One part in the context is divided into three aspects about the material capable of using in a fusion power reactor. Material selection in the first wall and plasma-facing components are two of the aspects. But it does not mention...

I have a PVC fitting that keeps cracking. The fitting consists of 2 parts. One piece is placed over the end of a flexible PVC ribbed hose, and the other is inserted inside the hose. The 2 parts act as a compression fitting to attach to the end of the hose. The hose typically has an outside...

Saw this yesterday and was thinking of Adam and Jamie afterwards. Several things in the movie were, IMNSHO, testable. 1. How much gunpowder would be needed to blow open a door made of iron reinforced wood that is 100mm or so thick? 2. Can you make a flying guillotine out of a shield? (A...

Might sound really stupid, but will it be more economical if instead of wall, a WIDE trench filled with water from adjoining ocean and river is allowed to flow in. With both the ends of the trench connected to the ocean, we can allow water to flow in during high tides, and flown out during low...

How would you find the friction of a box being pushed against a wall with a force of 200N and a weight of 100N?

Homework Statement An isolated conductor has a net charge of +14.0 × 10- 6 C and a cavity with a particle of charge q = +4.30 × 10-6 C. What is the charge (a) on the cavity wall and (b) on the outer surface? Homework EquationsThe Attempt at a Solution So I understand that B is just adding the...

Homework Statement I was recently assigned a project of, tl;dr, building a wall to reduce the maximum force during a collision. Let me start by describing the setup as best as I can. First, here's an image: These aren't the exact track and carts we're using, but they provide a great...

If there is no velocity and the fluid is moving still, then there is no kinetic energy, would there be no pressure exerted on the walls? Or perhaps there is a basal level of kinetic energy of the molecules as they are vibrating?Lastly, how can there still be flow if the pressure gradient is...

Hi everyone, this is a real world problem following the sinking of a narrowboat in 2014. The boat caught on the side of the lock as the water level dropped, and the resultant combination of pitch and heel resulted in the boat taking on water at the stern and sinking - luckily with no loss of...

Homework Statement Figure attached A uniform ladder is 10 m long and weighs 400 N. It rests with its upper end against a frictionless vertical wall. Its lower end rests on the ground and is prevented from slipping by a peg driven into the ground. The ladder makes a 30 degree angle with the...

Homework Statement why the mean area enclosed within the boundary of the centerline of tube thickness is (0.035)(0.057) ? Is it wrong ? Second question , why for the ds it's 2(57) and 2(35) respctively ? what is ds actually ? Homework EquationsThe Attempt at a Solution for the first...

I have a pipe holding liquid at 80°C. The outside atmosphere is -2°C. The pipe gets a temperature gradient over the wall thickness. The outside fibers will thus restrain the inner fibers from expanding. I would like to know the increase in the inner dia of the pipe. I have found temperature...

Homework Statement Two average forces. A steady stream of 0.250 kg snowballs is shot perpendicularly into a wall at a speed of . Each ball sticks to the wall. Figure 9-49 gives the magnitude F of the force on the wall as a function of time t for two of the snowball impacts. Impacts occur with a...

Hi, this is my first forum post - sorry if I'm in the wrong place, or I've done something wrong! Homework Statement Here goes: There is a beam of 0.5m length hinged to a wall at a right angle with 200N mass at the end of the beam. This is supported by a wire T at angle 30°. The question asks...

Homework Statement In the notes , I don't understand that flange is thin , and the top and bottom surface are free of stress , can someone help to explain please? Secondly , why the q' is assumed to be q ' throughout the flange is assumed to be 0 ? why are they stress free ? We could see that...

Homework Statement The question is asking when a car hits a wall, will the car or the wall experience the greater force. 2. Homework Equations The Attempt at a Solution I believe it's the equal force because of Newtons 3rd law

On the heels of 4 major universities offering racially segregated living areas, at the request of some students, some people decided that didn't go far enough. http://reason.com/blog/2016/10/26/video-uc-berkeley-protesters-built-a-hum']This[/PLAIN] week at UC Berkley protesters decided to...

A 10 gram rubber ball and a 10 gram iron ball are thrown at a wall with equal speeds. The rubber ball bounces back at almost the same speed with which it was thrown at the wall, while the iron ball bounces back at half the speed with which it was thrown at the wall. Which ball exerts a larger...

Homework Statement the main question asks: "If the book is initially at rest, what is its speed after it has traveled 0.400 m up the wall?" Homework Equations ∑F = m*a vf2 = vi2 + 2 * a * d , when initial velocity is 0. The Attempt at a Solution So here's my free body diagram: and out of...