What is Solid: Definition and 1000 Discussions

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. L

    Solid cylinder with nonuniform volume charge density?

    Homework Statement A long, non conducting, solid cylinder of radius 4.2 cm has a nonuniform volume charge density ρ = Ar^2, a function of the radial distance r from the cylinder axis. A = 2.5 µC/m5. (a) What is the magnitude of the electric field at a radial distance of 3.2 cm from the axis...
  2. A

    Understanding Einstein's Solid: Calculating Multiplicity of Energy States

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  3. lonewolf219

    Can Gauss' Law Be Applied to a Non-Uniformly Charged Solid Sphere?

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  4. B

    Plasma: 4th State of Matter - Properties & Magnetic Separation

    Plasma, the fourth state of matter, is a gas that consists of ions and free electrons. If you cooled plasma would it become a liquid? A solid? What would be the properties of this plasma? would you be able to magnetically separate it?
  5. H

    Chemistry Classify each solid as a covalent, ionic, metallic, or molecular solid.

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  6. T

    Electric Field due to Solid Non-Conducting Cylinder

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  7. B

    Copper & Silver Nitrate: Applying to Daily Life

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  8. Z

    Using the Shell method to find the volume of a solid

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  9. S

    Solid of revolution about other lines

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  10. B

    Calculating Volume of a Solid Using Integrals

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  11. H

    Solid State Electronic Devices - Valence Electrons Question

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  12. T

    Calculating Density of Gas from Combusted Solid w/ Known Wt, Pres, Vol

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  13. S

    Vibrations of a particle in solid

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  14. T

    Electric field inside a solid conducting sphere carrying charge q.

    Homework Statement A solid conducting sphere carrying charge q has radius a. What is the electric field when r<a. Homework Equations EA=Qenclosed/εo The Attempt at a Solution I found it using gauss law where Q=density*V. I ended up with qr/(4pi*a3*εo)HOWEVER, my friend told me it should be...
  15. H

    Solid state physics-effective mass problem.

    Homework Statement Tha band structure of a simple cubic lattice is given by, E = E_{0}-A(\cos k_{x}a+\cos k_{y}a+\cos k_{z}a) where a is the lattice constant and A is a positive constant. Find the effective mass for the electron at the values of k corresponding to the top and bottom...
  16. D

    Special Cases for Gravity Force Inside Solid Objects

    ---------------------------------------------------------------------------- I know about the shell theorem and that the force of gravity due to the mass of the spherical shell is zero inside. I have some questions that may easily be answered for other special cases using the shell theorm and...
  17. D

    Calculating Gravity Inside Complex Spherical Bodies

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  18. K

    Roadblocks to burning Solid Thorium Fuel

    Hi all Maybe a juvenile question but throw it out there anyways I know India is heavily vested in thorium due to the abudance in that region. I was wondering why current vendors are not looking to develop a thorium burning reactor to market to these guys or at least a modificaion to...
  19. I

    Finding Volume of Solid w/ Semicircular Cross-Sections

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  20. J

    How do I find the volume of a described solid using integration?

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  21. G

    Find the volume of the solid obtained by rotating the region

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  22. J

    Optical absorption liquid vs solid

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  23. M

    Engineering Science: Torsion (Hollow Shaft replaced by Solid Shaft)

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  24. B

    Solid State Relay power source

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  25. S

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  26. G

    About magnet field in solid oxydes fuel cells

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  27. J

    What is the Volume of a Solid of Revolution Rotated about the x-axis?

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  28. I

    Solid property of inert gas- LJ potential

    Homework Statement Hi, We meet again PF, this time I am little stumped on the following question(link posted down). Homework Equations Link to the question "Question" The Attempt at a SolutionI think I get the gist of it for part (i) my calculated value for equlibirum separation is about...
  29. A

    Center of mass of solid hemisphere.

    Homework Statement I've just started with center of mass, and instead of the method in the book, I tried solving the center of mass for a solid hemisphere using angle as a variable, but the answer didn't match. A small disk of mass "dm" is taken, which subtends an angle "dθ" at the center.The...
  30. A

    Compute Solid Angle of Cone: θ | Hi Everyone

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  31. P

    Solid state physics: phonon density of state

    Homework Statement There is a Ar cube crystal with Lenard jones potential: V^{L.J.}=-\alpha/r^{6}+\beta/r^{12} We know the volume V, the parameters of the L.J. potential, and the mass of the Ar atom (m_{Ar}). Determine the phonon density of state. (D(ω)=?) Homework Equations...
  32. T

    Solid mechanics thermal stress of infinite cylinder

    Homework Statement My problem is to calculate the Thermal stress of a Cylindric shell with inner radius a and outer radius b the inner surface is experiencing Temperature T1 and the outer surface is experiencing T2 with T1>T2 assuming that the linear thermal expansion coefficient is a, the...
  33. P

    Moment of inertia of a solid sphere derivation.

    Hello! I'm trying to derive the formula for the moment of inertia of a solid sphere, and I keep running into a strange solution. I set up the infinitesimally mass of an infinitesimally thin "shell" of the sphere: dm = 4\rho\pir2 dr And then solved for the moment of inertia: I = \intr2dm =...
  34. Spinnor

    Shoot a bullet at a half-infinite isotropic elastic solid.

    Say we shoot a bullet that travels in the theta = 0 direction (we are in spherical coordinates). Say the bullet strikes and sticks to a half-infinite isotropic elastic solid that begins at the theta = 90 degrees plane. Is it true that longitudinal waves generated by the bullets impact will be of...
  35. K

    Rotational motion of a solid sphere of mass

    A solid sphere of mass m is released from rest from the rim of a hemispherical cup so that it rolls along the surface. If the rim of the hemisphere is kept horizontal, find the normal force exerted by the cup on the ball when the ball reaches the bottom of the cup.
  36. A

    Center of mass of solid hemisphere by using angle as variable.

    Homework Statement I've just started with center of mass, and instead of the method in the book, I tried solving the center of mass for a solid hemisphere using angle as a variable, but the answer didn't match. A small disk of mass "dm" is taken, which subtends an angle "dθ" at the center.The...
  37. M

    Uniform Solid Sphere Moment of Inertia Calculation

    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...
  38. E

    Exploring Element Band Gap: What Determines the Size and How Can It Be Altered?

    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...
  39. A

    Finding Volume of Solid in First Octant with Bounded Polar Equations

    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...
  40. T

    Finding maximum or minimum of volume of solid revolved about a region

    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...
  41. M

    Evaporation of a solid in water vapor.

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

    Engineering science- Replacing hollow shaft with solid shaft

    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...
  43. C

    Finding the Mass of a Solid in 3d

    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...
  44. M

    Solid State Heat capacity optical and acoustic

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  45. T

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    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...
  46. J

    Angular acceleration of solid sphere on frictionless yoke unde no slip roll condition

    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...
  47. G

    Solid State Physics - p-n junctions

    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...
  48. K

    Cant solve heat equation on semi infiniate solid

    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...
  49. S

    Rotational Mechanics Problem (Rotating solid wooden disk)

    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...
  50. S

    Conductivity titrations that doesn't produce a solid precipitate and water?

    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...
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