Solid Definition and 1000 Threads

Homework Statement We have a steel rod with density ρ = 7,90 kg/m^3. When it's horizontally on the floor, it's length is L = 6,00m. The rods surface area A is a circle with radius r=0,04m. Steel has Young modulus E=2,1 \cdot 10^{11} Now the rod is lifted up so it's vertically straight...

Hi, I have a question concerning solid of revolution. The bowl-shaped volume formed by rotating the area circumscribed between y=bcosh(1) and y=bcosh(x/a) around the y-axis was given to us by the instructor as pi*b*int [x^2*d(cosh(x/a))] between 0 and a. My question is why are the integration...

Homework Statement The solid bounded by the surface z=y2 and the planes x=0,x=1,z=1 I have a question regarding the limits of integration, would it be incorrect, if when I graphed z=y2 I changed it to a familiar xy graph instead I just graphed it as if z was y and x was y. Pretty...

Homework Statement 2.0 moles of a monatomic gas interacts thermally with 2.0 moles of an elemental solid. The gas pressure decreases by 50 degrees C at constant volume. What is the temperature change in the solid? I missed this day in class and I have no idea where to even begin...

Hi! I am about to start a project on the effectiveness of conformal cooling in injection molding, where i will be designing the cooling channels for a mold. However, i do not know which software will be better for designing the cooling channels and performing the finite element and heat...

Energy, Angular Momentum, Torque, solid ball rolling down loop track? help!? A solid brass ball of mass .280g will roll smoothly along a loop-the-loop track when released from rest along the straight section. The circular loop has radius R = 14.0 cm, and the ball has radius r<<R. (a) What is...

Hi there! I run into a situation where I can't go on. It's about a thermal analysis, I already made a simulation using Ansys but I also want an approach made "by hand". In order to simplify the case I made this example: We have a metallic bar inside the soil. The bar is at 100ºC and the...

Homework Statement I need help setting this integral up in spherical coordinates, the region above the xyplane, inside the sphere x^2+y^2+z^2=2 and outside the cylinder x^2+y^2=2 The Attempt at a Solution \int^{2\pi}_{0} \int^{\pi/2}_{\pi/4} \int^{\sqrt{2}}_{0}...

Hello, I am struggling with what was supposed to be the simplest calc problem in spherical coordinates. I am trying to fid the center of mass of a solid hemisphere with a constant density, and I get a weird result. First, I compute the mass, then apply the center of mass formula. I divide...

Homework Statement I have an energy function as follows: E = \dfrac{\hbar^2}{2m_e}k_x^2+E_0\left(n_y^2+1\right) Where E_0 = \dfrac{\pi^2\hbar^2}{2m_eL_z} I am asked to plot this energy for x\in ]-L_z/2;L_z/2[ I know everything but not the relation between k and x?. The Attempt at a...

Homework Statement I want to convert this into polar and use double integral to find the volume of the solid in this region. I just need help setting this up region Q: x^2+y^2≤9, 0≤z≤4 I know this is a cylinder with a height of 4. I am just having trouble incorporating this height into the...

\frac{}{}Homework Statement Starting from S(E,N)=c(N)+3Nk[1+LN(\frac{E}{3Nh\nu})], derive a version of the Entropy, S(E,N) of an ideal solid that is extensive, that is, for which S(\lambdaE,\lambdaN)=\lambdaS(E,N) Homework Equations The Attempt at a Solution Basically have to...

Hi, What is the difference between alloy compounds and solid solutions I understand so far that solid solutions are homogeneous in composition, which must mean that one, two or more different atoms have same crystal packing structure when combined to form a solid solution.

Homework Statement James Bond and Dr. No are engaged in fisticuffs on a board overhanging a pool. Dr. No now pulls out his weapon. oh no!. Bond is in trouble again. Bond quickly calculates the torques and leaps off the left end of the board leaving Dr. No on the right. Is Bond safe? That is...

Hi, So here is the contents of this Elementary Particles course: introduction to families of particles , relativistic kinematics applied to reaction cross-sections and decay rates; symmetries and conservation laws, isospin, strangeness, charm, beauty; parity and CP violation in weak...

Homework Statement the function is y = -x^2+6x -8 suppose a city is surrounded by a ring of mountains and these mountains can be illustrated by rotating the above function around the y-axis. Find the volume of the Earth that makes up these mountains. Suppose the city suffers from air...

Homework Statement Consider the region of the x y plane given by the inequality: x^2 + 4x + y^2 - 4x - 8 ≤ 0; If this region rotates an angle of π/6 radians around the line given by the equation x + y = 0, it will create a solid of revolution with surface area equal to (i)...

Hey guys, I know it late its a little past one here. But I'm doing an assignment due tomorrow at I've been stuck on the last question for at least an hour. Find the volume of the solid obtained by rotating the region bounded the curves Y=absolute value of x. and y = square root of (...

Hello, I'm new in here. And now i am in research about elektron transfer between solid material. Is this possible and reversible ? Does anyone ever try this ?

Homework Statement Let E be the solid enclosed by the paraboloid z = x2 + y2 and the plane z = 9. Suppose the density of this solid at any point (x,y,z) is given by f(x,y,z) = x2. Homework Equations x2 + y2 = r2 = 9; r = 3 ∫∫∫E x2 The Attempt at a Solution The limit of z is...

Homework Statement This was a question from my homework. I got it wrong, even after asking my professor about it, and even though I can't get credit for it now, I'd like to know where I went wrong if anyone can help sort me out! "Water is drawn from a well in a bucket tied to the end of a...

Hi All, I am still trying to wrap my head around the five light year stick and the idea that if you push an object, it moves because longitudinal waves of compression force (?) are sent through the medium of whatever the object is made of: https://www.physicsforums.com/showthread.php?t=386687...

I got these people trying to say that you can orientate a solid oblong so that it looks half the length and width with the only residule effect that it looks like it is slanted sideways a bit. Does anyone know what it is or are they crazy. I think they might be crazy. How do you explain this to...

What would be the pattern of electric field lines 'inside' a solid charged sphere..?

Hello.. The query is regarding thermal conduction of heat from a solid body: Suppose we have a long metallic rod which is insulated on the curved surface and one of the bases. If we supply Q amount of Heat for a small time to the rod from the non-insulated end, initially the temperature of...

I am using the textbook called Classical Mechanics by John R. Taylor. Z = 1/M ∫ ρ z dV = ρ/M ∫ z dx dy dz On page 89, example 3.2, it says: "For any given z, the integral over x and y runs over a circle of radius r = Rz / h, giving a factor of πr2 = πR2z2 / h2." I wish the book would...

Homework Statement Find σ , the differential cross section, starting from the expression below and integrating over solid angle Ω Homework Equations dσ/dΩ = r2sin2θ The Attempt at a Solution dσ = r2sin2θ dΩ I remember that dΩ = sinθ dθ dμ and doing the μ integral from 0...

Homework Statement y = {\frac{1}{4+x^2}} on the interval [0,2], revolving about y = -1 Use either the disk/washer or shell method to find the volume. Homework Equations v = pi\int (outer radius)^2-(inner radius)^2\,dx v = 2pi\int (radius)(height)\,dy x = \sqrt{\frac{1}{y}-4}...

I've been told this is a trick question, but I don't understand why: How would I describe the solid generated by 2∏∫ x/(1+x2)dx on [0,2] How I would do it I would rewrite the intergal as 2∏∫ x * 1/(1+x2)dx and apply substitution. I would then use the volume of disks method and integrate the...

Homework Statement The volume of a solid obtained by rotating the region enclosed by x=0, y=1, x=y^5 about the line y=1 can be computed using the method of disks or washers via an integral.Homework Equations V= ∏\int(R^2-r^2)dx The Attempt at a Solution I have attempted this problem many...

How to rearrange particles in matter? The goal is to create a device that moves each and every particle of a particular object to a new location at the same time thus transforming this object into another.(e.g., a spoon into a cup by rearranging its molecules or one chemical element...

Homework Statement An isolated solid copper sphere of radius .12m has a positive charge of 6.4x10^-9 C. i) calculate the electric potential at a point .10 m from the center of the sphere. ii)calculate the electric potential at a point .24 m from the center of the sphere. The Attempt at a...

can one construct a solid Klein bottle - a 3 manifold whose boundary is a Klein bottle as follows. - Start with a solid cylinder and identify the two bounding disks by a reflection. - The boundary becomes a Klein bottle but is this a smooth manifold whose boundary is this Klein bottle? - If...

I'm not that familiar with the inner workings of solid state relays, and I'm seeing an unusual anomaly in my circuit that I'm not quite sure how to explain. For my job, I'm running tests on some sensors. One of the requirements for the test is to turn the power to the parts on and off...

Homework Statement A 3/4-in.-diameter rod made of the same material as rods AC and AD in the truss shown was tested to failure and an ultimate load of 29 kips was recorded. Using a factor of safety of 3.0, determine the required diameter (a) of rod AC, (b) of rod AD. Homework Equations...

If you have a tube and a solid cylinder of the same dimensions and density and rolled them down an inclined plane the 'tube' would cover the same distance in less time?

Homework Statement We have a uniformly charged solid sphere whose radius is R and whose total charge is q. I'm trying to find the electric field inside a (r<R). The correct answer must be: E=\frac{1}{4 \pi \epsilon_0} \frac{q}{R^3} r \hat{r} How did they get that answer? The Attempt at a...

Homework Statement For a charged solid metal sphere with total charge Q and radius R centered on the origin: Select "True" or "False" for each statement: 1.If the solid sphere is an insulator (instead of metal) with net charge Q, the net charge on the inside of the solid sphere is...

Let f(x)=9-x^2. Let A be the area enclosed by the graph y=f(x) and the region y>=0. Suppose A is rotated around the vertical line x=7 to form a solid revolution S. So, using the shell method, I was able to find the indefinite integral used. I found the shell radius to be (7-x) and the shell...

I bought a cheaper set of roller blade wheels (you get what you pay for). With new wheels installed I had to work much harder to take longer on my usuall route. The new wheels had a hardness of 82a. The original wheels had a hardness of 80a and the last set had a hardness of 85a. The new wheels...

Homework Statement estimate the volume of the solid z=-2(x^2+y^2)+8 between the two plates z=4 and z=0Homework Equations In question like this, should I use triple integrals or double integrals in polar coordinates? I'm stuck in between which to use, because the question asks to estimate the...

Dear Physics Forum Users Commonly, the relative permittivity of liquid water is reported to be \epsilon_r = 78.0\epsilon_0, \epsilon_0 being the dielectric constant of the vacuum. For ice (solid water), \epsilon_r = 4 \epsilon_0 (heard it in a talk once). Is it correct to interpret the...

On finding the center of mass of a solid hemisphere i came up with some different result. Here's what i did... consider a small ring at a distance r from the center of the hemisphere and one more ring at a distance of r+dr from center of the ring. let, mass of the small element formed...

Homework Statement 2. A solid copper sphere of radius 15.0 cm carries a charge of 40 nC. Find the electric field (i) 12.0 cm, (ii) 17.0 cm and (iii) 75 cm from the centre of the sphere. (iv) Explain how your answers would change if the sphere were hollow. Homework Equations...

Dear all, In Java and using Java3D library, I have created a GUI for viewing finite element quad element meshes. I am facing two problems with the graphics: 1. In order to draw the meshes, I draw the quads and the edges separately so that I am able to remove one and leave the other on...

Recently I started thinking about it, because apparently you get different results. At first, I thought you would weigh less on a carpet (according to the scale), because the carpet supports some of your and the scale's weigh. But thinking deeper into it, I actually figured it shouldn't make a...

Homework Statement Hi I am looking at a unit sphere. Two squares are projected onto the sphere on opposite ends, as shown in figure 1 (the figure only shows one square, the other one is at the opposite end). There are two more sets of these squares, each set in its own dimension, so there...

[b]1. The solid angle subtended by a 100 cm^2 circular detector at a distance of 1 m is ______steradians. [b]2. Ω = A/r^2 and A =∏r^2 (area of a circle) [b]3. I originally tried to find r by solving 100 = ∏r^2 and I got r = 5.6. I then tried to plug into the first equation for Ω only to...

Homework Statement Solid ball of charge with radius R and volume charge density ρ(r) = ρ0r2, centred at the origin. I have already found the electric field for r<R and r>R and also the potential at the origin by using the formula: V = -∫E.dl Now i want to find the potential at the...

Homework Statement Find the volume of the solid obtained by rotating the region bounded by the given curves about the specified axis. Homework Equations y = \sqrt{x-1} , y = 0, x = 5; about y = 3 The Attempt at a Solution I already completed graphing it, but not really sure how...