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. Y

    Is a solid cylinder considered thick or thin?

    I have a solid cylinder of diameter 40mm and length 14mm and I have used plane stress approximations in my calculations so far. I know for to assume a thin walled cylinder/tube the wall thickness needs to be less than 1/20 of tube or cylinder diameter. However, what I have found so far is that...
  2. J

    B Are energy bands in solid state timeless?

    The wave function or Schroedinger equation is timeless, correct? You can reverse the equations and forward it. Our arrow of time comes due to decoherence in macroscopic object. How about energy bands in solid state. Do you consider it as timeless wave function, or is it decohered?
  3. busarider29

    Detecting a metallic object through solid metal

    I have looked at various off-the-shelf industrial sensors for detecting objects but I cannot find anything that will detect metal through metal. I have a metal plate that is 1/4" thick. I need to detect a metal object on the other side of the metal plate. The metal object on the other side of...
  4. D

    Help with neutron scattering in solid state physics

    Hello fellow physicists, I have a homework assignment which is to make a scientific essay (10-15 pages long) on neutron scattering in solid state physics. Our teacher is kind of the worse and he hasn't specified what he wants it on. He just said what I'm telling you: "An essay on neutron...
  5. Jarvis323

    Moving through Air, Dust, and Solid Objects with Warp Drive

    What would happen if you tried to fly through obstacles using warp drive? Distorting space so that two points are closer wouldn't get around the fact that there might be obstacles (e.g. air molecules, space dust, empire destroyers) that you would bump into along the way right. Would all of that...
  6. M

    I How Does Solid Angle Affect Power Calculation in Radiometry?

    I have a doubt regarding the role of the solid angle when calculating the power(W) with the brightness of the source I'm observing with area Asource. I was given the definition: with A the Aantenna. If now I take as an example the picture below to calculate W, we conisder as solid angle the one...
  7. C

    Moment of Inertia of a Solid Cylinder With a Wedge Removed

  8. Will26040

    How do you approximate between the Cp of a gas and a solid?

    I have the Cp of Benzoyl peroxide (BPO) in gas form (454.39 J/molK). What approximation could I make to find the Cp of solid BPO as I cannot find this info online? thanks
  9. G

    Polarization of a solid sphere of nonconducting material

    a) Just using the equations gives us: surface charge density = ## \rho_{\rho s} = kR^2 ## volume charge density = ## \rho_\rho = -4kR ## b) I am not sure here but the Q on the shell is the same as within. If that's the case we can use gauss law to find Q which I guess is the total charge. ##...
  10. P

    A What is the meaning of ##d\Omega## in solid angle integration?

    Anyone have any idea how to perform the following two integrals? ##\int d\Omega n_{i}n_{j}## and ##\int d\Omega n_{i}n_{j}n_{k}n_{l}## where the n is a unit vector.
  11. dasil12a

    3D Solid State Simulation Software

    How did you find PF?: Google I am studying the mechanical/electrical nature that govern certain nano-fabricated crystalline structures. Can someone with experience please recommend a 3d Solid State Simulation software that will allow me perform the following: Allows individual 3D placement...
  12. madafo3435

    Why is the field within a solid conducting material zero?

    .
  13. H

    I Where does this solid angle come from?

    I found this paper https://arxiv.org/abs/quant-ph/0412216 We have an interferometer with to arms. The firsr has a couple of HWP's inclened by an angle theta and the second has the crossed couple. A mixed state is in input. i look to the figure withe the Bloch sphere. i see 2 paths on it. one...
  14. cwill53

    Using the solid angle to simplify an integral when deriving Gauss' Law

    I'm a bit confused on the derivation above. I understand what the goal of the derivation is, as it derives Gauss's Law using the solid angle, but i was wondering if someone could kind of fill in the steps the author skipped and explain the use of the solid angle.
  15. F

    I Coexistence of Solid and Liquid Matter: Conditions for Existing One Phase?

    I think in solid or liquid phase, there are many molecule having a very large speed due to random character in moving.So the liquid or solid matter must co-exist with other phase because some molecules escape from surface of solid or liquid matter.Then is there any condition for existing only...
  16. S

    Physics Solid State Physics or Quantum Electronics/Optics

    For which field is there more demand in the industry? And is knowledge of quantum electronics/optics useless without having a phd, as I see most job offers ask for a doctorate degree. Are the skills and knowledge from quantum electronics transferable to engineering positions or is what you...
  17. agnimusayoti

    Potential inside a uniformly charged solid sphere

    Well, in this problem, I try to use $$d \tau '= \mu ^2 \sin {\theta} {d\mu} {d\theta} {d\phi}$$ With these domain integration: $$0<\mu<r$$ $$0<\theta<\pi$$ $$0<\phi<2\pi$$ , I get $$V=\frac{1}{4\pi \epsilon_0} \frac{3Qr^2}{2R^3}$$ This result is wrong because doesn't match with Prob 2.21, which...
  18. Hamiltonian

    Finding the center of mass of a solid hemisphere

    for this derivation, I decided to think of the solid hemisphere to be made up of smaller hemispherical shells each of mass ##dm## at their respective center of mass at a distance r/2 from the center of the base of the solid hemisphere. also, I have taken the center of the base of the solid...
  19. C

    A How are the thermal expansion of a solid and the stress tensor related?

    My idea is this: tensor stress is directly related to the internal pressure of a solid. That is to the force that the neighboring atoms exert each other in relation to a unit of surface. When I heat a solid we can have the phenomenon of thermal expansion: this is connected to the fact that a...
  20. brotherbobby

    Hollow and solid spheres floating in liquid

    The two situations are shown in the figures alongside. The hollow sphere has a thick heavy rim that compensates for the air inside it - both spheres have the same mass ##m_B## and radius ##r_B##. Since the bodies have the same mass ##m_B##, the mass of liquid displaced is the same ...
  21. S

    Ratio of acceleration of two solid cylinders released on two inclined planes

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  22. LCSphysicist

    The Effect of Increasing the Size of a Solid on Its Entropy

    Does increase the size of the solid body increase its entropy? I was thinking about it using the Einstein model of solid. S = k*lnΩ Ω = (q+n-1)!/((q)!(n-1)!) I am not sure how this question should be answer, i think if we talk about rigid bodies, the question don't even have sense, but about...
  23. rxh140630

    Drilling a hole through the center of a solid sphere

    The volume of the sphere = \frac{32{\pi}r^{3}}{3} The answer given at the back of the book is (\frac {32}{3} - 4\sqrt{3}){\pi}r^3 To drill a hole completely through the sphere, the hole would have to have a length of 4r. To get the answer in the back of the book, it requires setting the...
  24. T

    Exploring the Grand Partition Function for an Einstein Solid

    $$Q_{(\alpha, \beta)} = \sum_{N=0}^{\infty} e^{\alpha N} Z_{N}(\alpha, \beta) \hspace{1cm} (3.127)$$ Where ##Q## is the grand partition function, ##Z_N## is the canonical partition function and: $$\beta = \frac{1}{kT} \hspace{1cm} \alpha = \frac{\mu}{kT} \hspace{1cm} (3.128)$$ In the case of an...
  25. Kayla Martin

    How to calculate a solid angle in steradians from arcminutes?

    I tried $$\Omega = \pi(\frac{\theta}{2})^{\frac{1}{2}}$$
  26. LCSphysicist

    Solid disk rolling down an inclined plane -- Some conceptual questions

    I was always a little confused about the rolling down of a body, let's say, a sphere. It's know that to body rotate, from the rest, in a referential frame on the ground [inertial], is necessary a friction, that will just act like a medium that transforms kinetic energy of translation into...
  27. A

    Rotational Mechanics -- A solid sphere is rolled on a rough surface

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  28. hagopbul

    I Biological solid state physics

    Hello all: I was wondering are we have a name for protein structure , or we consider them amorphous? Any one did a phono propagation in protein molecules ? Protein folding and phonons any relationship? When peptides came together and start to form the protein dose phonons/photon propagation...
  29. T

    The variation of the information content of a large Einstein solid

    For ##q >> N ##. ##\Omega \approx \left( \frac{eq}{N} \right)^N \text{ } (2)## (Schroeder, An introduction to thermal physics (2.21)). Can we argue that: ##\Delta I = - \Delta S \text{ } (3)?## How large can ##\Delta N##, be? Thank you for your time.
  30. D

    Compute the flux of a vector field through the boundary of a solid

    is it correct if i use Gauss divergence theorem, computing the divergence of the vector filed, that is : div F =2z then parametrising with cylindrical coordinates ##x=rcos\alpha## ##y=rsin\alpha## z=t 1≤r≤2 0≤##\theta##≤2π 0≤t≤4 ##\int_{0}^{2\pi} \int_{0}^{2} \int_{0}^{4} 2tr \, dt \, dr...
  31. ahelpinghand

    Need an odorless additive that can to turn liquid into solid

    I would like to know of any compound that I can use to add to a liquid that can turn it into a solid. I would like the liquid to be air drying and form a solid but slightly fragile structure. Almost semi-brittle, where if hit or crushed, small pieces of crystals would break off. Is there such...
  32. G

    Gauss-Theorem on a solid dielectric sphere

    The load system formed by the point load and the load distribution generates two regions in space corresponding to r<1m and r>1m, i.e. inside and outside the sphere. Given the symmetry of the distribution, by means of the Gaussian theorem we can find the modulus of the field at a distance r from...
  33. binbagsss

    Droplets on a solid / liquid surface (engineering)

    Why is it important to study this? And what makes them interesting to study?
  34. Sebastiaan

    How To Name a Mixture of a Solid and a Liquid

    Alright, I'm trying to find out what the Chemical naming convention would be of a Mixture Aluminium (nanoparticles) and Liquid Oxygen. The Mixture is mended as a monopropellant in a lunar rocket engine.
  35. hagopbul

    I Studying the air layer over a solid object

    Hello all : i was wondering is it possible to study the air layer over a solid object at the interface ? using spectroscopic methods ? for example density ?
  36. Charlie Cheap

    Tube amplification vs solid state

    I am certain this has been answered...but I missed it. Why do so many guitar players swear by TUBE amps? My son-in-law says they just sound better. Because I was a TV/Radio service tech for 20 years with a degree from Elkins Institute, he asks me why? My guess was, maybe amplifying a signal...
  37. M

    Find the volume of the solid formed by the rotation around the y=0

    Hi, I find this... Please tell me your opinion on this. Thanks.
  38. N

    MHB Calculate volume of a solid rotating around the y-axis

    Sorry if i made any language errors, English isn't my first language. Question: The limited area in the plane is created when the space between the line y=1 and the graph to the function f(x)=3*x/(x^2+1) rotates around the y-axis. Calculate the volume of the solid.I want to sum up all the...
  39. Wi_N

    Calculating the surface area of a solid of rotation

    For some reason I have become very unsure but my gut feeling says i can calculate y=(1-x^(a/b))^(d/c) I already know the formula for calculating the volume. but can transfer the whole thing as a function of y(x) and take the integral then as a single integral?
  40. Yalanhar

    Calculate the rotational inertia of a solid hexagonal

    What I did: ##\frac{dm}{dA} = \frac{M}{\frac{3\sqrt3 R^2}{2}}## ##dm = \frac{2M}{3\sqrt3 R^2} dA## (1) ##dA=3\sqrt3 rdr## (2) (2) in (1) ##dm = \frac{2M}{3\sqrt3 R^2} 3\sqrt3 rdr## Now in the integral ##I = \int \frac{r^2 2Mrdr}{R^2}## How can I solve the integral interval? I think I...
  41. Arman777

    Electrostatic Energy of a solid sphere with a cavity

    I tried to use ##W = ε_0/2 \int E^2d\tau## for all space. So I find that ##E = \frac{(R^3 - b^3)\rho}{3ε_0r^2}## where ##\rho## is the charge denisty. So from here when I plug the equation I get something like $$W = \frac{(R^3 - b^3)^2\rho^2 4 \ pi}{18ε_0} \int_{?}^{\inf}1/r^2dr$$ Is this...
  42. jisbon

    Calculating the volume of the solid in this graph

    Homework Statement: Base of solid is the region bounded by graphs ##y= \sqrt x## and ##y=x/2##. The cross sections perpendicular to the x-axis are squares whose sides run across the base of the solid. Find volume of solid. Homework Equations: - As stated above, I will want to calculate the...
  43. A

    Solid State What is the best online course that follows Kittel for solid state physics?

    Hi, I am currently studying solid-state physics course from Charles Kittel's "introduction to SSP" I searched more on youtube to get lectures to follow the book of Kittel but failed. Really I would appreciate if anybody advises me online source which can help me to comprehend the contents of...
  44. Nimarjeet Bajwa

    How can we find the center of mass of a solid cone?

    is this method even possible? anyways here is my attempt Step1) y= 2H/3 ( H is the height of the cone) step 2) we take the density (ρ)= 3M/π R2 H. The problem i am facing is to Find "dm"
  45. lfdahl

    MHB Volume of the solid obtained by rotating R around the line y=x

    Let $R$ be the region $\left\{(x, y) : 0 \leq x \leq 1, 3^x − x − 1 \leq y \leq x\right\}$. Find the volume of the solid obtained by rotating $R$ around the line $y = x$.
  46. T

    Entropy increase of solid vs liquid

    A hypothetical question. Heat Q is transferred from water to a metallic solid. Both have same heat capacities and the same initial temperature. Now since molecules in a liquid are more randomly oriented than a solid, will the entropy decrease of the liquid be more than the entropy increase of...
  47. T

    Brillouin's negentropy in an Einstein solid

    Hello! I would like to apply Brillouin's negentropy principle to an isolated Einstein solid, with a decreasing number of oscillators. We assume that the number of oscillators are initially N and the energy quanta (q the number) remain constant. Firstly, I would like to know if this principle is...
  48. K

    Thermal Expansion (liquid and solid) Question Help

    Summary: Help with volume and length expansion question Hi, I am struggling with this question. I understand that beta = 3 alpha so you use this to sub into the volume expansion equation. Is this correct? Can someone please provide a step by step instruction on how to do this question? Thank you !
  49. M

    A Calculating Light Intensity on a Target Using Lamp Setup

    Hi, I am trying to simulate necessary flux values on a car due to solar radiance. I'm trying to attain the necessary flux values using a lamp setup. I have the lamp specifications in Watts but I need to convert them into radiance values (W/m2/sr) for my application. I would like to know how to...
  50. T

    I Can we consider this system as an Einstein model of a Solid?

    Hello Everyone! I am interested in examining the case of an isolated Einstein Solid (ES) with a decreasing number of oscillators. The total amount of energy of the ES is considered fixed. Whenever an oscillator abandons our model, it "leaves behind" the amount of energy it contained, so that the...
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