Solid Definition and 1000 Threads

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...

In my calculus exam, I would like to know for all of the questions that I am 100% right (who wouldn't?). I can be sure of this for most basic questions using my graphics calculator (fx-9750gii) and some simple maths. One thing I want to know how to be "completely sure" to solve are solid of...

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 have worked with softwares that help me simulate circuits (Hpice, Proteus, MultiSim), but is there a software that helps me simulate devices right from the level of the atom? For instance, I should be able to create a pattern of boron with silicon atoms, and then be able to replicate it 1...

Homework Statement This isn't a homework question, I am writing up my scribbled notes from todays lecture and have got stuck on some calculus, and lost the thread of the argument. Last week, we integrated Plancks law to find B(T) = ∫ Bv(T) dv = 2∏4(kT)4 / 15c2h3 Then...

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...

Hi, I'm taking an introductory course on solid state physics next semester, and the book the Professor has chosen is the 8th edition of Kittel. I have heard MANY bad things about this book, so I'm wondering if I should just use an earlier edition or another book entirely. Any...

Dear Physics Forum community, I am posting here as a last resort, so any guidance/references would be much appreciated. As a small part of my project, I need to calculate the natural frequency of metallic solid spheres. All I have been able to find on the web is the Schummann Resonance...

Other than the fan and hardrive, nothing else seems to be moving...

Homework Statement Having recently learned the disk/shell/washer method for finding the volume of a solid of revolution, I'm trying to apply similar methods to derive the formula for the surface area of a cone (and hopefully after that, that of a sphere). The region that is revolved around...

So I'm supposing a scenario where you have energy transfer into a solid and waves propagating out from the impact point and i want to measure the energy at different distances from the "epicenter" with sensors. the relationships I've been pointed to are basically conservation of energy at the...

What's the best way to do Finite Element stress analysis? By that, I mean I'm looking for the best set of general fundamental assumptions to start with. In your opinion. I ask because I'm trying to write a computer code in Matlab that I can use as a general tool for who-knows-what sort of...

Homework Statement The thermal conductivity of Cu at room temperature is 400 W/(mK). Use this value to determine the average time between collisions, \tau. Compare this value with the electrical conductivity.Homework Equations Not sure. I take T=300K for room temperature. From a book and with...

Homework Statement A beam has a solid square cross section of 100mm and is simply supported by two supports 3m apart. Calculate the dead load that can be safely supported when applied to the middle of the beam. Homework Equations Solid square cross section of beam: 100mm Material...

Homework Statement Beginning with Icm = Integral of r^2 dm from r1 to r2, find the moment of inertia of a solid sphere about any tangential axis. Homework Equations Icm = Integral of r^2 dm The Attempt at a Solution I set up the infinitesimally mass of an infinitesimally...

Homework Statement The X-rays diffraction diagramm of a cubic crystal shows lines for the following angles 2 \delta = 31.47º, 39.74º, 47.58º, 64.71º and 77.59º when the X-rays have a wavelength of 1.54 \times 10 ^{-10}m. Determine the crystal stucture of the net, the Miller indices of the...

Homework Statement Hi guys, I don't reach the correct answer to an exercise. I'm following Ashcroft's book. I must find that the reciprocal of the bcc Bravais lattice is a fcc one and the reciprocal of the fcc Bravais lattice is a bcc one. Homework Equations If a_1, a_2 and a_3 are...

Homework Statement Have to do a write up of an experiment on specific heat capacity of metals. Tested 50g of nickel and lead, each heated to 90C and then put into 50g of water and measuring the change in its temperature. Found that lead has a lower specific heat capacity. Homework Equations...

A solid steel shaft is subjected to a torque of 45 KN/m. If the angle of twist is 0.5 degree per meter length of the shaft and the shear stress is not exceed 90 MN/m^2 (I) find the suitable diameter of the shaft . Take C = 80 GN/m^2 (II) Maximum shear strain we can solve the question by...

First post. Great to be here. :) So, I'm stuck in deciding which of these courses to take next semester. I'm a current rising sophomore at UT Austin who has just switched from EE to physics-still nervous about that decision, but that's a separate topic. I've already got Waves(the first...

This question may sound a bit odd, but is there a relatively simple way(by simple, I mean inexpensive) to determine how much acrylamide is in a certain type of food(e.g. French fries, potato chips)?

Hi, What is the best solid state physics video course available online. So far the best one i have found is this one .. but it is just introduction to Solid State Physics

Homework Statement Use direct integration to find electric field inside a uniformly charged non-conducting solid sphere. The radius of the sphere is R, observing point is at a way from center of the sphere while a<R. Homework Equations Use Coulomb's law only. No Gauss law is allowed. You may...

I was reading through a book on statistical physics when i came across this sentence: "An Einstein solid has two degrees of freedom for every oscillator." How is this possible? I picture an oscillator (ex. mass on spring) to move only in one dimension, thus one degree of freedom. Where does...