Solid Definition and 1000 Threads

In object-oriented computer programming, SOLID is a mnemonic acronym for five design principles intended to make software designs more understandable, flexible, and maintainable. The principles are a subset of many principles promoted by American software engineer and instructor Robert C. Martin, first introduced in his 2000 paper Design Principles and Design Patterns.The SOLID concepts are

The Single-responsibility principle: "There should never be more than one reason for a class to change." In other words, every class should have only one responsibility.
The Open–closed principle: "Software entities ... should be open for extension, but closed for modification."
The Liskov substitution principle: "Functions that use pointers or references to base classes must be able to use objects of derived classes without knowing it". See also design by contract.
The Interface segregation principle: "Many client-specific interfaces are better than one general-purpose interface."
The Dependency inversion principle: "Depend upon abstractions, [not] concretions."The SOLID acronym was introduced later, around 2004, by Michael Feathers.Although the SOLID principles apply to any object-oriented design, they can also form a core philosophy for methodologies such as agile development or adaptive software development.

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  1. A

    Calculating the Limit of an Einstein Solid Specific Heat

    So, I can't really find this limit: \lim_{T \to \infty} \ 3Nk {(\epsilon/kT)}^2 \frac{e^{(\epsilon/kT)}}{{(e^{(\epsilon/kT)}-1)}^2} This is actually the formula for the specific heat of an Einstein solid, which is pretty easy to derive but I haven't been able to calculate the limit to show it...
  2. C

    Linear Expansion of Steel Girder Due to Temperature Change

    Homework Statement A girder made of steel. The length of the girder is 3.77 m. In the middle of the girder there is a fracture. The temperature rises 32° C. Homework Equations Find the height that the girder rises from the middle, if it is fixed at both ends. The linear expansion...
  3. A

    How to mobilize solid molecules

    i was discussing with ma friend about the possibilities of inducing more vibration to the molecules in a solid matter... but we could not find a process to do that even though its not practical wanted to know some thing that is theoretical... hope some one is going to give new ideas..
  4. 1

    Crystal spacing of a solid surface, Bragg's law

    Homework Statement In a particular Low Energy Electron Diffraction (LEED) study of a solid surface, electrons at 45 eV were diffracted at \phi = 53 degrees. Calculate the crystal spacing d. Homework Equations n\lambda=2dsin(\phi) \lambda = hc/E wavelength = c/v E = vh(n + 1/2) Note here v...
  5. L

    Find the volume of a solid using known cross sections?

    Homework Statement The base of a solid is the region between the parabolas x = y2 and x = 3 - 2y2. Find the volume of the solid given that the cross sections perpendicular to the x-axis are: a) rectangles of height h b) equilateral triangles c) isosceles right triangles, hypotenuse on the...
  6. L

    Finding Volume of the solid, Integral

    Homework Statement Question Reads: A circular disk x ^2 + y^2 <= a ^ 2 , a > 0 is revolved about the line x = a. Find the volume of the resulting solid. Homework Equations v = integral(a, b) (2pi)y [F(y) - G(y)] dy The Attempt at a Solution Im currently confused, should i...
  7. B

    Finding Surface Area of a Solid of Revolution

    Homework Statement Find the surface area generated by rotating y=5-4x^(3/2), 0\leq x\leq 1 about x=2.Homework Equations SA = 2\pi\int_{a}^{b}(r\cdot ds)dx The Attempt at a Solution I simply filled in the formula for the given question, and I'm getting stuck at integration time. SA =...
  8. Q

    Solid angles and particle velocities

    This should be a simple question, but I haven't found a clear explanation anywhere yet. Suppose that there are a bunch of particles in a gas, with their velocities "uniformly distributed over solid angles", and I want to find out what fraction of particles are traveling with velocities in a...
  9. B

    Gauss' Law: Solid Non-conducting Cylinder

    Homework Statement A long, solid, non-conducting cylinder of radius 8 cm has a non-uniform volume density, ρ, that is a function of the radial distance r from the axis of the cylinder. ρ = A*r2 where A is a constant of value 2.9 μC/m5. What is the magnitude of the electric field 7 cm...
  10. H

    Deformation of solid combined with momentum and kinematic

    Homework Statement A light elastic string has natural length 1 m. One end of the string is attached to the fixed point O and particle P of mass 4 kg is suspended from the other end of the string. When hanging in equilibrium, P is 6/5 m below O. Find the modulus of elasticity of the string...
  11. G

    Rotation of a solid body about CM?

    We know when a body is given a impulsive force in total vaccum, it rotates along with translation about the centre of mass. Now the question is why does it rotate only about the CM and not any other axis. We al know this seems obvious due to insinct but how can the theory explain it. Does any...
  12. E

    Hoop stress in solid disc from thermal contraction

    Hi, I have been looking at hoop stresses and the information I have found hasn't been all that useful to me as I am having a hard time converting the thermal contraction of a system into a pressure for the equation (stress=a+b/r^2). This is the thick walled hoop equation The disc is a few...
  13. S

    2nd semester calc question : calculating volume of solid of revolution

    Homework Statement The solid formed when the region bounded by y = x^2 and y = 2 - x^2 is revolved about the x-axis Homework Equations disc method with respect to x-axis the integral of : (pi * (f(x)^2 - g(x)^2)) The Attempt at a Solution When I square each function and...
  14. L

    Volume change when liquid goes to solid.

    Hello! I need some help regarding a simple matter... How do I derive an equation for the increase in volume when a liquid goes to a solid state when I know the density of the liquid?
  15. E

    Volume of a solid based on number of atoms

    This is a silly doubt i guess... Homework Statement When you know an atom's radius you can easily determine its volume by considering it's a sphere. But when you're dealing with solids, that is, a set of atoms... and then you have bands insted of orbitals... this differente...
  16. P

    Solid State Tesla Coil: Basics & Advice

    Hi everyone, I am have been looking here for a long time, but today is my first day registered. I will be active from now on =). As my first post, I would like to know about the basics and advice about the solid state tesla coil. I would like to do it for my final year project. Is it advisable...
  17. B

    Why is CO2 liquid less dense than CO2 solid

    I can sort of understand why water is denser than ice, but for CO2 I cannot understand why it is the other way around. Here is my best shot at understanding it: I imagine H2O's solid structure as a hexagon due to the hydrogen bonds, where each point represents one atom. When these bonds are...
  18. K

    I'm sure deposition is a change from a gas to a solid.

    I'm sure deposition is a change from a gas to a solid. But can someone explain in details.
  19. M

    Sharing Singlets: Exploring Valence Bond Solid States

    Hello I have come across this inexplicable fact mentioned in somewhere that for a chain of S = 1 spins, the adjacent bonds can all be in a singlet state i.e. singlets can be shared in this case (forming valence bond solids) but not, for example, for |S| = 1/2, the latter point being clear. I...
  20. G

    Finding Velocity and Angular Speed of a Rolling Cylinder

    Homework Statement A solid cylinder of radius 20cm is released from a 2.5 high incline. If it rolls down without losing any energy to friction, find the cylinder's velocity at the bottom of the incline and the angular speed at the bottom of the incline. Homework Equations The...
  21. B

    Lagrangian density of linear elastic solid

    I need the general expression for the lagrangian density of a linear elastic solid. I haven't been able to find this anywhere. Thanks.
  22. Simfish

    How much faster is RAM compared with a solid state HD?

    If the difference isn't that much, then could a computer theoretically have A HUGE amount of RAM, simply by setting aside a significant portion of the SSD as virtual memory? Maybe a SSD external HD could also be used as virtual memory (for those of us who don't have internal SSD drives yet)
  23. N

    Is the Fermi Level at E = 2ta for Tight-Binding Dispersion?

    Homework Statement Hi Say I have the tight-binding dispersion given by E = -2ta cos(ka). When plotting this, then is it correct that the Fermi level is at the energies satisfying E = 2ta, i.e. a straight line in a (k,E) plot?
  24. N

    Should i take intro solid state phy without background of quantum phy?

    I do not know anything about quantum physics, but due to some timetable clashes i hv to take intro solid state and intro quantum phy in the same semester. One advisor said its ok and he said intro solid state phy is only abt memorizing crystal, but another advisor said it would be tough...
  25. L

    Fraction of energy dissipated when solid cylinder placed on table

    A uniform solid cylinder is set spinning about its axis and is then gently placed, with the axis horizontal, on a rough horizontal table. What fraction of its initial kinetic energy is dissipated in sliding friction before the cylinder eventually rolls smoothly along the plane? The only...
  26. A

    Volume of Solid: Calculating Y=2-X^2 Rotated about Y=1

    Homework Statement hi i can't seem to make head or tail of this question. here it goes; find the volume of the solid generated by rotating the area enclosed by the curve y= 2-x^2 and the line y = 1, about y=1. i am not sure how to start. can someone please explain? thanks...
  27. S

    Surface area of solid of revolution with undefined derivative

    Hello there. Suppose I have a function: y=3x^{2/3}-1 I want to find the surface area of the solid formed when the part of the curve between x=0 and x=8 is revolved about the x-axis.The curve crosses the x-axis at a point (1/3)^{3/2} The derivative of the function is...
  28. A

    Triple Integral, Volume of a solid

    Homework Statement Well, first of all, I'm not english spoken, so sorry for the mistakes. I was trying to calculate the integral below: \int \int \int_{V} (xy+z) dxdydz where V is a region in R^{3} bounded by the sphere x^2+y^2+z^2<=9 the cone z^2<=x^2+y^2 and the plane...
  29. Y

    Solid State physics, studying for a re-exam

    I have gone trough all the material for a solid state physics course I had earlier this exam, and there are three question I actually can't solve, even with all the lecture notes. Here they are: 1. An electron of mass m moves in a square lattice, spacing a. The nearly free approximation...
  30. G

    Solid state physics and chemistry

    As solid state physics studies the structure of materials, it is often important to study and to understand molecular theory. This means that you should, for instance, know very well the properties of the states of electrons in atoms with more than one proton in the nucleous. You should also...
  31. M

    How Does Polishing Affect Heat Flow in a Gold Ring?

    Homework Statement You are polishing a 10.0 g gold ring. (treat as an ideal solid). After doing this for a minute, you find that the ring is hot, having increased the temperature by 15 deg C. Calculate the heat that flows into or out of the system and specify which direction. Homework...
  32. Q

    Pressure of Solid Homework: Show P = -dΦ₀/dV + γU/V

    Homework Statement Show that the pressure of a solid is given by P = -\frac{\partial\Phi_0}{\partial V} + \gamma \frac{U}{V} \Phi_0(V) is the potential energy of the solid when all atoms are at rest in their equilibrium positions and V is the volume of the solid. U is the internal energy...
  33. K

    Finding the Volume of a Solid Below a Plane and Above a Paraboloid

    Homework Statement The volume of the solid below the plane: z=2x and above the paraboloid z=x^2 + y^2. I need help setting this one up, I can handle the evaluating. The Attempt at a Solution I just don't know.
  34. S

    Determining Bravais Lattice from Primitive Translation Vectors

    hi, i don't know how to determine bravais lattice from primitive translation vectors.The problem is as: A crystal with one atom basis, has a set of primitive translational vectors as a1=3i, a2= 3j and a3= (3/2)(i+j+k). What is the bravais lattice.
  35. P

    Solid sphere Kinetic Energy problem

    Homework Statement A solid sphere is released from rest at the top of an incline of height H and angle 30°. The sphere then rolls down the incline without slipping until it reaches the bottom of the incline, at which point the speed of the center-of-mass of the sphere is found to be 65 cm/s...
  36. D

    How to define a solid cyclinder or any solid objects parametrically?

    How to define a solid cyclinder or any solid objects parametrically? I can't figure out what do I do with the z axis for example a Cylinder : x = 0.5*cos(theta) y = sin(theta) 0*pi <= theta <= 2*pi This will make an eclipse. But wad about z? I know we have to stretch z to the...
  37. J

    Use polar coordinates to find the volume of the given solid.

    Homework Statement Bounded by the paraboloid z = 4 + 2x2 + 2y2 and the plane z = 10 in the first octant. Homework Equations The Attempt at a Solution Plugging in 10 for z I got 3=x2+y2. From this, I set 0\leqr\leq3\sqrt{}. I wasn't sure what to do with the first octant, but I...
  38. H

    Solid Shape Volume by Disk Method Problem

    Homework Statement The base of a certain solid is an equilateral triangle of side a, with one vertex at the origin and an altitude along the x-axis. Each plane perpendicular to the x-axis intersects the solid in a square cross section with one side in the base of the solid. Find the volume...
  39. P

    Using Vicks Theorem to Calculate Average of Bose Operators

    Vick's theorem help us to find average value of product of even number of operators. For example look the case of four Bose operators \langle \hat{b}_1\hat{b}_2\hat{b}_3\hat{b}_4 \rangle =\langle \hat{b}_1\hat{b}_2 \rangle \langle\hat{b}_3\hat{b}_4 \rangle +\langle \hat{b}_1\hat{b}_3 \rangle...
  40. G

    How does movement through solid objects work?

    If there was a metal bar: - with no flexibility - one end is at earth, on a pivot - the other end is at the nearest star and free to move If you moved the bar up and down at the star end, would you see the bar pivot here on Earth immediately or would it take the same time as the speed of...
  41. K

    Potential Energy of a solid sphere and a thin disk

    A solid sphere with radius r is placed on top of a thin disk with radius R. The contact point is the center of the disk. Both objects are uniform and have the same mass M. Calculate the gravitational potential energy of the system. Take the potential energy to be zero when the sphere and the...
  42. P

    Forces on a Solid Disk: Determining F3

    Homework Statement Three forces of F1, F2, and F3 are applied to a solid disk with a mass of 3.6 kg and radius of 2.9 meters. F1 is directly above the center of the disk with a magnitude of 47 Newtons directed in the positive x direction, F2 is directly to the right of the center and has a...
  43. P

    Valance and conduction band in solid.

    Hi, I have a very basic question on formation of valance and conduction band. It is said that conduction band is above the valance band. So In a hypothetical lithium molecule formation(for example purpose) : If 100 Lithium atoms combine together, then 1S shell is split into 100 1S shells (one...
  44. Telemachus

    Does Iterated Integral Define a Solid?

    Homework Statement Hi there, I have this iterated integral \displaystyle\int_{0}^{2}\displaystyle\int_{0}^{2-y}\displaystyle\int_{0}^{4-y^2}dxdzdy, and the thing is, does it define a solid? because I think that as it is given it doesn't, but I'm not sure. I think that the cylindric paraboloid...
  45. L

    Detailed and well explained Solid state textbook?

    Hey, I've done a search here on this forum as well as the internet and can't find very many detailed Solid State physics books reccomendations. I am on a 3rd year class in solid state. The lectures are almost exclusively mathematics, as well as the notes. Id love for a book to follow the...
  46. L

    How do atoms behave in a solid state?

    This concept of when things have higher kinetic energy, their molecules and atoms move more never got to me. I don't get how something having more kinetic energy will make the atoms spread apart and liquify, if enough radiation gets to an object (infrared) in order to reach its melting point, I...
  47. D

    Solid mechanics challenge question

    Hi all! Good evening Here is the Question: This question is given as a challenge extra credit task, and is a part of a course called solid mechanics 2 that deals more with shear strain and strain matrices. While trying to translate the question I used the term "strength" instead of...
  48. B

    Find the volume of the solid generated by revolving the area.

    Homework Statement Find the volume of the solid generated by revolving the area bounded by y = sec[x], y= \sqrt{2} - \pi/4 \leq x \leq \pi/4 about the x-axis Or [PLAIN]http://img838.imageshack.us/img838/1552/mathprobq6.jpg Homework Equations a = lower limit = --\pi/4 b = upper limit = \pi/4 V...
  49. A

    MoI of a Solid Sphere Derivation

    I'm aware of many, many solutions to this on the web (and on the forum) that I can follow, but I'm trying a different way (there are many, after all) and I can't figure out why it's not working, and I'd love to know where my logic is flawed. I have a solid sphere, and I'm splitting it up into...
  50. R

    Which Element Is Ideal for Solid State Physics?

    Homework Statement I have just started solid state physics course and we got an assignment to choose one element that we are going to work with. Which element is interesting from a solid state physics point of view (and relatively not too difficult to work with)? Homework Equations...
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