Solid Definition and 1000 Threads

Find the moment of inertia of a uniform solid sphere of mass,m and radius,a about an axis through its centre. I have tried to solve it but I get the different answer, I don't know where I have done mistake. Please! check and correct my solution below:- Consider a volume element, dv of the...

Might be an easy question (or not). What determines the band gap of an element? As far as I know, silicon is the most efficient single-element semiconductor because of it's small (but nonzero) bandgap. Next (as far as I know) is Selenium. I'm aware there are more efficient compounds, but...

Homework Statement find the volume of the solid bounded by the graphs of the given equations: r=1+cos∅ z=y z=0 (the first octant) Homework Equations V=\int\int rdrd∅ The Attempt at a Solution So, I've been having trouble deciding what to integrate from and to. I...

Question: For c>0, the graphs of y=(c^2)(x^2) and y=c bound a plane region. Revolve this region about the horizontal line y= -(1/c) to form a solid. For what value of c is the volume of this solid a maximal or minimal (Use calculus 1 techniques). First, I found the volume of this...

Can a solid, no matter how small, even a single cell, be evaporated with water vapor from a pool of water?

Homework Statement Hi, thanks for looking! Appreciate it! Right, the question is For a HOLLOW shaft determine, max torque induced, pilot second moment of area, max shear stress at outer edge, and max angle of twist induced in the shaft, with a material modulus of rigidity of 110...

Homework Statement Find the mass of the solid bounded by the cylinder x^2+y^2=2x and the cone z^2=x^2+y^2 if the density is \delta = \sqrt{x^2+y^2} [b2. The attempt at a solution[/b] I had some trouble looking at how to set up the limits on this integral. What I came up with was: 2...

Homework Statement Sketch the solid whose volume is given by the following integral and then evaluate this integral: ∫(0≤r≤2)∫(0≤θ≤2π)∫(0≤z≤r) (r) dzdθdrThe Attempt at a Solution So, I kind of cheated and evaluated the integral first. So I have ∫(0≤z≤r) (r) dz = rz, from z=0 to z=r, which I...

Homework Statement m=6kg r=0.18m Fapp=33N I'm struggling to understand how to answer this question and correlate the linear force applied to rotation without being given the coefficient of friction causing the rotational motion. The question states that a solid sphere of 6kg is...

Homework Statement An ohmmeter is sometimes used to determine the "direction" of a diode by connecting the ohmmeter to the diode one way and then reversing the ohmmeter leads. If the ohmmeter applies an emf of .5V to the diode in order to determine resistance, what would be the ratio of...

Hi All, I am having issues trying to work out a task my employer has given me and was wondering if there is someone who could help. Question: A Semi-infiniate solid (L=3M) x>0, is initially at temperature zero. At time t=0, a constant temperature Uo>0 is applied and maintained at the face...

I have the working for part d) but I don't understand certain parts, so my problems lie with part d), f) and g) Homework Statement 3. A solid wooden disk is suspended as shown: it has mass 7.70 kg and radius 0.219 m . It is rotated from rest about its vertical axis, reaching an angular...

A pretty simple question, but I was just wondering if it was possible to be able to do a conductivity titration for a reaction that does not create a solid precipitate and water? I was thinking no because the only reaction that i thought would work for conductivity was an acid-base...

Homework Statement Use the method of Lagrange multipliers to find the maximum and minimum values of the function f(x, y) = x + y2 subject to the constraint g(x,y) = 2x2 + y2 - 1 Homework Equations none The Attempt at a Solution We need to find \nablaf = λ\nablag Hence...

Finding the critical point and its nature. With solid attempt! Homework Statement Find all critical points of the function f(x, y) = xy2 - 2xy - 2x2 - 3x +7 and determine their nature. Homework Equations none The Attempt at a Solution I know that to find the critical points you must...

Homework Statement Find the volume and the centroid of the solid E that lies above the cone z=√x^2+y^2 and below the sphere x^2+y^2+z^2=49. Homework Equations The Attempt at a Solution My bounds were: \theta=0 to 2\pi \varphi=0 to \pi/4 \rho=0 to 7cos(\varphi) So my integral...

So I want to use this solid state relay, to fast switch an electromagnet. About 2 times a second. Weight: 112g Size:5.9 x 4.5 x 2.3cm Color : Grey Fast switching Reduced electromagnetic interference Output voltage: AC 24-380V Output current: 25A Input voltage: DC 3-32V Control Method: DC to...

Homework Statement basically, my question is this, in relation to this diagram, https://www.physicsforums.com/attachment.php?attachmentid=12482&d=1202140386 wouldn't the electric field between the solid sphere and the hollow sphere be a uniform field? Homework Equations The...

Homework Statement Silicon at T= 300K contains acceptor atoms at a concentration of Na = 5*10^15 cm-3. Donor atoms are added forming an n-type compensated semiconductor such that the fermi level is 0.215 eV below the conduction band edge. What concentration of donor atoms are added...

Homework Statement Consider an electron gas in ONE and TWO dimensions i.e N electrons in a metal wire with length L or in metal sheet with area L^2. Pictures must be drwan of the fermi 'sphere' and the Fermi 'surface' . Why are the two words in quotation marks ? Homework Equations...

1. Consider the function f(x) = arcsin(2x^2 - 1). Write down, but do not attempt to solve, a definite integral in terms of y, which when evaluated will give the volume of the solid of revolution formed by rotating the graph about the y-axis. 2. Endpoints are at (-1, pi/2) and (1, pi/2)...

As part of my Intel Science Fair project "How to make Hydrogen a viable alliterative" I read that at 3,500,000 psi Hydrogen will become a "Solid" so that you can have more power in less space which will make the car much more efficient. I am doing this on a 1/10 scale. My question is what...

Homework Statement Homework Equations n\lambda = 2dsin(\theta) The Attempt at a Solution a) solving for d I get \frac{n*\lambda}{2*sin*(\theta)} = d substituting in the first value 50.85 to solve for d, with n=1 I get d= 1.754*10^-10m How do I solve the miller indices from the inter...

I have a B. Sc. in Electrical Engineering and I would like to work with photovoltaics / solid state device physics. My undergraduate degree is not quite enough to let me work in that field outright. So I'm looking to do a graduate degree. I applied for a 2-year M. Sc. in Physics program and I...

Chemistry: Reactions in Solution, But Not In Solid Form? Homework Statement "Calcium chloride and sodium carbonate are two ionic solids. If the solids are placed together, nothing seems to happen. However, if they are mixed in water, the following chemical reaction occurs: * See relevant...

Homework Statement We have to trace a pumpkin on graph paper and then find it volumne when rotated around the y-axis. Upon doing so we have 2 pieces we can do. One is a semi circle and the other just a rectangle. Refer to this image: Where we can see the diameter of the circle is 13.5...

Homework Statement The base region of a solid is bounded by y=x, y=(x-1)^2, and x = 1. The cross sections are semicircles perpendicular to the x-axis. Write a riemann sum and definite integral. Homework Equations The Attempt at a Solution First, I wrote down the formula...

Homework Statement A uniform solid disk of radius R and mass M is free to rotate on a frictionless pivot through a point on its rim (see figure below). The disk is released from rest in the position shown by the copper-colored circle. (a) What is the speed of its center of mass when...

Hi there, I should probably know this (attempting to do a PhD in physics!) but is there a way to differentiate between longitudinal and shear acoustic waves in a solid? I know that seismologists know which is which by using the time of flight difference for the two types of waves and the...

Homework Statement x=2y^2 x=0 y=+-6 rotated around y Homework Equations integral 2pi*x(f(x)dxThe Attempt at a Solution integral from -6 to 6 of 2pi*y*2y^2 dy but i get something far less than the correct answer

Homework Statement The base is the semicircle y = \sqrt{9-x2}(Square root of 9-x2.. i don't know why the formatting isn't showing up) where -3 <= x <= 3. The cross section perpendicular to the x-axis are squares. Homework Equations -3\int3 = A(y)dy A(y) = area of cross section...

I know that the first solid solid state device is: A semiconductor diode what about transistors? Is it not a solid state device? Explain me the difference between solid state device and semiconductor device.

Hi All, I had a question about this problem I was doing and was hoping to see if I did it right. Homework Statement Using Disk or Washer method Find volume of the solid generated by revolving the region bounded by y=sqrt(x), y=2, x=0 about the line y=2.Homework Equations Disk Method...

Homework Statement Find the volume of a solid bounded by the functions y=1-x2 and y=0 revolved around the x-axis Homework Equations (don't know how to show integrals) A=Pi * the integral from xa to xb of [f(x)]2-[g(x)]2 The Attempt at a Solution First, to find the lower and upper...

Here is the problem: The electron concentration in a region of silicon depends linearly on depth with concentration of 5x10^15 cm^-3 at surface (x=0) and 10^15 cm^-3 at depth of x=500nm. If the vertical electron current density in this region is constant at Jn=100 A/cm^2, calculate the...

Hi, I was reading my astrophysics textbook and came across solid angles. I'm not sure I fully understand, for example there was a problem in the book that went as follows. The attached "math.jpg" shows a light source (yellow) in the centre of an arc. The problem is 2D, but the arc is...

It is very common to see in the literature negative formation energies reported for point defects in solids using different simulation techniques ranging from Density Function Theory to Molecular Dynamics. The authors rarely comment on what does that mean physically. I will mention here two...

Are all acid have covalent structure in solid state?

I am very much interested in design engineering, development of consumer, scientific and medical devices. My favourite aspects of engineering include mathematics, CAD and computational engineering. I would say that my key strengths lie in analytical, mathematical thinking and very strong...

Homework Statement If a solid is generated by rotating the line (x=4tan(y*pi/3)) on the y-axis. Find the volume between the area 0≤y≤1. Homework Equations I know that, when slicing a section (A(x)), I will generate a circle. This gives me two of the dimensions (by using area of a...

How to dehydrate a solid crystal? I have a solid crystal with structural channels in it which are filled with water molecules. The size of each channel is 2.5 to 5 angstrom and a water molecule is 2.7 angstrom on its longest side. What is the best way to dehydrate it? I have tried heating it...

Homework Statement A solid ball of mass M and radius is connected to a thin rod of mass m and length L as shown. What is the moment of inertia of this system about an axis perpendicular to the other end of the rod? Image: http://imageshack.us/photo/my-images/35/helpfy.jpg/ Homework...

I am curious as to whether the force of solid sphere can be considered to be originating entirely at its center when the force is not of \frac{1}{r^2} nature. It is said that the field inside a uniform spherical shell is zero for any \frac{1}{r^2} type force and not for any others. It would...

The definition of Beam solid angle: For an antenna with single main lobe, the Beam solid angle defines as: The solid angle \; \Omega_A\; where all the radiated power would flow with radiation intensity equal to maximum and constant inside the Beam solid angle \; \Omega_A\;. The book gave...

Look at a simple single - component system. And PT diagram for this system. Suppose that supstance we looking at has three phases solid, liquid and gas. In that case we have critical point between liquid and gas phase, but not between solid and liquid phase. Why? Why solid - liquid coexistence...

Hello, I have to find the maximum rpm of the shaft that has ring mounted on the shaft with interference fit of 0.002". I want to know at what rpm the ring will come loose from the shaft? and If I run the shaft at 7000rpm at 400 degree Celsius, is the interference fit of 002" enough...

Hi all. I've just hit a block in the following question: [Find the volume of the solid...] "The region in the first quadrant bounded by the curve y = x^2, below by the x-axis, and on the right by the line x = 1, revolved around the axis x = -1." I've tried nearly 2 hours figuring the...

Homework Statement The question asked is to make a bowl out of polynomial equations rotated around the y axis. The bottom of the bowl has to have a maximum at the center and a minimum at some distance from the center. The equations I want to use are x^2+10, 1.3x^2 and -.7x^2 + 4. The...

I understand the surface of the sphere is 4\pi sr. where the area of one sr is r^2. My question is why d\Omega = sin \theta \;d \theta \;d\phi? Can anyone show me how to derive this. Is it because surface area dS = (Rd\theta)(R\; sin\;\theta\;d\phi)\;\hbox { so if }\; \Omega = \frac S {R^2}...

Homework Statement y= -(x/6) + b, find the volume as this solid is rotated 360 degrees around the Y axis Homework Equations If I were given the interval at which I needed to find the volume and/or the value of B I could easily do this using the formula: [pi] Integrate: (R(y))2 dx...