What is System: Definition and 1000 Discussions

A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and expressed in its functioning. Systems are the subjects of study of systems theory.

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  1. anemone

    MHB Real Numbers $a,\,b,\,c$ Solving System of Equations

    Find all the real numbers $a,\,b$ and $c$ that satisfy the following system of equations: $\begin{align*}a + b + c &= 1\\ \dfrac{a}{ 1 - a}+\dfrac{b}{1 - b} + \dfrac{c}{1 - c} &= 6ac + 6bc = (a + 1)(b + 1)\end{align*}$
  2. B

    Spring-mass system in circular motion has a maximum angular speed?

    and this is my solution for question (d), it may seems that $$R=(k)/(k-m\omega^2)R_0$$ so that $$\omega ≠ \omega_i =√(k/m)$$ but $$\omega_c <\sqrt{k/m}$$ is always true, ##\omega_i## corresponds to the limit case when ##F_max## is infinitely large Besides, I don't know other Physics prevents...
  3. Nexus99

    How Does Friction Affect System Movement?

    Can't visualize how the system moves, can anyone help me?
  4. TempleSweeper

    A Exploring Symmetry Breaking Phenomenon in a Physical System

    In some experiments of a complex physical mathematical system, we found some symmetry phenomenon, very similar as symmetry breaking phenomenon, say, as translatable sysmmetry etc. These symmetry (breaking) phenomenon occurs in most of the parts of the system or some parts of the system. Can you...
  5. B

    Choosing proper coordinates in a complex 2 pulley system

    FBD Block 1 FBD Block 2 FBD Pulley B I'm mainly concerned with the coordinate system direction in this problem, but just to show my attempt, here are the equations I got from the system. ##-T_A + m_1g = m_1a_1## ##T_B - m_2g = m_2a_2## ##T_A - 2T_B = 0## Using the fact that the lengths...
  6. F

    Gravity Fed Farm Animal Watering System

    I am trying to design/build a large self-filling drinking station, aka water bowl, for my goats and cow (see design attached). It's a takeoff of a dog's self-filling water bowl, i.e., uses gravity and vacuum to automatically refill the bowl as the water in the bowl is drank. The rain barrel is...
  7. R

    I Is the energy of this system conserved?

    In this system (consisting of just the gas) heat is transferred to the gas by means of a reservoir. So this means energy is added to the system. Does this necessarily mean that the work done on the lead shot due to an increased pressure will equal the heat that enters the gas? We are assuming...
  8. mcastillo356

    Verifying Coordinate System for Electric and Magnetic Forces

    The attached file is the coordinate system I've used a) $$\vec{E}=\dfrac{\vec{F_e}}{q}=\dfrac{1,10\cdot{10^{-13}}\hat{j}\;N}{1,6\cdot{10^{-19}}\;C}=6,88\cdot{10^5}\hat{j}\;N/C$$ b) $$\sum{\vec{F_{net}}}=\vec{0}=\vec{F_e}+\vec{F_m}$$...
  9. Lren Zvsm

    How big could a system of caverns be without collapsing?

    In the horror novel, the Descent, by Jeff Long, Earth has a system of deep caverns so extensive that they constitute a virtual "sub-planet," a kind of partial lower deck in the Earth's crust, whose mutated human inhabitants have horns and decorate their bodies with extensive scarification...
  10. K

    A Equipartition theorem and Coupled harmonic oscillator system

    Dear all, While simulating a coupled harmonic oscillator system, I encountered some puzzling results which I haven't been able to resolve. I was wondering if there is bug in my simulation or if I am interpreting results incorrectly. 1) In first case, take a simple harmonic oscillator system...
  11. K

    B System of linear equations: When are we guaranteed a unique solution?

    I was reading about systems of linear equations. Even if we have the same number of unknowns and equations, we may still have infinitely many or no solutions. But if in addition to that the determinant of the matrix of coefficients does not vanish, then does it necessarily imply that we have a...
  12. S

    B Tidal Locking question about the Earth-Moon system

    This section of the Wikipedia article on tidal locking https://en.wikipedia.org/wiki/Tidal_locking#Mechanism states: (Note : A is the earth; B is the moon) I am having trouble understanding that last "whereas" bit (bold font). It seems to me that if we consider lower and lower rotation speeds...
  13. K

    Torque on Left Foot of Man in Rotating System

    I saw that the solution states that the torque about the center of mass is zero, since the man does not rotate about its center of mass. However, I then thought about taking the torque about the left foot (so the right foot for the man's POV). Hence: $$\tau_{left} = \tau_{0} + \textbf{R}\times...
  14. S

    B Does Removing Planets Affect the Sun's Energy?

    If I take away the planets in the solar system and leave the sun alone, would the sun have less energy than before?
  15. Kaguro

    Flux in a rotated cylindrical coordinate system

    ##\vec F= 2x^2y \hat i - y^2 \hat j + 4xz^2 \hat k ## ## \Rightarrow \vec \nabla \cdot \vec F= 4xy-2y+8xz## Let's shift to a rotated cylindrical system with axis on x axis: ##x \to h, y \to \rho cos \phi, z \to \rho sin \phi ## Then our flux, as given by the Divergence theorem is the volume...
  16. LCSphysicist

    System subject to a driving force

    The displacement of the end of a spring varies as , the block on the spring is subject to a viscous force proportional to the velocity. Spring stiffness k. (a)Find the displacement of the block: (b)When γ -> 0 First of all, i have a doubt i we could start saying the component of the force is...
  17. LCSphysicist

    Solve this vector system containing sum and dot product equations

    Seems to me the answer is a specific vector: The second forms a plane, while the first X is just a vector. The intersection between the λX that generates the (properties of all vectors that lie in the...) plane (i am not saying X is the director vector!) How to write this in vector language?
  18. J

    MHB Finding the Unique Solution of a Polar System with Variable Radius?

    Hello! Brand new to the forums, hopefully someone here can help me out. Paths start out at the edge of a circle and "flow" along a polar equation that determines phi based off the initial phi (phi0) and a variable radius (ie. as your radius grows, your phi is changing). Hopefully this image...
  19. LCSphysicist

    Analysing System of Equations: 2kx2 + kx1 = mx2 & 2kx1 + kx2 + kXocos(wt) = mx1

    Well, i think the important here is the system, what you think about?: -2kx2 + kx1 = mx2'' -2kx1 + kx2 + kXocos(wt) = mx1'' After this, is just solve, i found: x2 = (k*xo*cos(wt)*(4k/m - 2w²))/(2m*(k/m - w²)*(3k/m - w²)) The cool is that if we put w equal the two normal frequency x2 tends to...
  20. T

    Solar System Dynamics page at NASA/JPL

    Stumbled across this and found it interesting. Solar System Dynamics pages at JPL (Jet Propulsion Lab)/NASA. Has Bodies, Orbits, Physical Data, Tools, etc. https://ssd.jpl.nasa.gov/?site_map Cheers, Tom
  21. LCSphysicist

    How to calc the period of this mass spring system?

    This is a problem very easy to deal with if we consider the effective spring constant, however, i want to avoid this solution, and see how to justify the period of this motion just by analyse the forces or the energy, what seems a little hard to me. First of all we would need to find the force...
  22. F

    Blockchain as a decentralized system

    Hello, I am learning about blockchain this summer. I sort of get the big idea (skipping the middle man, encryption based decentralized system where everyone that is on the database can see everybody else transactions). Isn't the fact that everyone can see any transaction unsafe and against the...
  23. S

    MHB Solve System of 4 Equalities: x+y+z+w=22, xyzw=648

    Solve the following sustem 1) x+y+z+w=22 2) xyzw=648 3) \frac{1}{x}+\frac{1}{y}=\frac{7}{12} 4) \frac{1}{z}+\frac{1}{w}=\frac{5}{18}
  24. T

    Rotation around a non fixed axis + linear motion of a system

    I have had a thought experiment in my head for a while now and I am unable to find clear enough examples/info that deal with similar issues, to solve it on my own. This is why I hope that someone in this forum can at least point me towards a solution or provide hints as to where should I be...
  25. Yellotherephysics

    A Functional Determinant of a system of differential operators?

    So in particular, how could the determinant of some general "operator" like $$ \begin{pmatrix} f(x) & \frac{d}{dx} \\ \frac{d}{dx} & g(x) \end{pmatrix} $$ with appropriate boundary conditions (especially fixed BC), be computed? And assuming that it diverges, would it be valid in a stationary...
  26. T

    Calculating Forces in a Pulling System: Fp, Wp, Wm

    Fp = Fg +Ff Fp = (21*9.81*sin(31)) + (0.2*21*9.81) Fp = 147.30 Fp*d = 147.3 *4.5 Wp = Wm = 662.87 = 663 J I am not sure what I am doing wrong. Should I subtract the force of friction from the force of gravity? Have I assumed that the pulling force is equal to the sum of gravity and friction...
  27. Amaterasu21

    How are ancestors classified in a cladistic system?

    Hi all, When I first learned about cladistics, it seemed like an elegant and objective way of classifying life - forget about subjective physical similarities, classify purely based on scientifically testable ancestry, and have all taxa be monophyletic clades, so everything in one taxon is more...
  28. core1985

    Which system of units is coherent for mechanics?

    So, should i write All of these as accodring to wiki pedia maxwell applied coherence concept to FPS, CGS, and SI is already coherent so answer will be All of these ?? Am i right or MKS because question is restricted to mechanics only ?
  29. hilbert2

    A 2-electron system under compression

    I did some calculations for the ground state energy and wave function of a system of two electrons put in a finite-depth 2D potential well. Regardless of the shape of the potential well (square or circular), the expectation value of the electron-electron distance ##\langle r_{12}\rangle =...
  30. Sunny Huang

    A How to calculate the interband velocity matrix in a graphene system

    In graphene system, the velocity operator sometimes is v= ∂H/ħ∂p, and its matrix element is calculated as <ψ|v|ψ>, i.e., v_x = v_F cos(θ) and v_y = v_F sin(θ) [the results are the same with Eq. 25] for intraband velocity. Recently, I see a new way to calculate the velocity matrix (Mikhailov...
  31. LCSphysicist

    Solving a Closed System w/Conservative Forces: Is E1=E2 Always True?

    This problem is very easy to solve considering that the two particles belong a closed system under action of conservatives force. My doubt is if it is possible to solve the problem by consider one particle by time, that is: Suppose that we know the particle m one is under gravitational force...
  32. PhysicoRaj

    Reaction torque in a traction system

    Hello PF, I am building a traction assembly for a self balancing bot project and I am having some conflict with my intuition and practical testing results. The setup consists of a motor mounted to a chassis, the shaft coupled to a wheel that rests on a surface with non-zero friction. Below...
  33. S

    Comp Sci RSA system with p=17, q=11 and e=3. Find m corresponding to c=156

    OFFICIAL SOLUTION: d=e^(-1) mod 160=107 mp= c^(d) mod p=7 mq:=c^(d) mod q=7 MY THOUGHTS: I understand how d = 107, but I got that by using m = (17-1)(11-1) = 160. What I don't understand is the next two lines (from the official solution). I am aware of the P = C^d mod n (decryption) formula...
  34. S

    MHB Solving System of Equalities: x^2-y\sqrt xy & y^2-x\sqrt xy =3

    Solve the following :A) x^2-y\sqrt xy=126 y^2-x\sqrt xy=-63 B) \frac{x} {y}+\frac{y}{z}+\frac{z}{x}=\frac{y}{x}+\frac{z}{y}+\frac{x}{z}=x+y+z=3
  35. S

    MHB Solve System of Equalities: x^2+xy+y^2, x^2+xz+z^2, y^2+yz+z^2

    solve the following system: x^2 +xy +y^2=37 x^2+xz+z^2=28 y^2+yz+z^2=19
  36. S

    MHB Solve System of Inequalities: 2x+3y-4, 3x-4y+5

    Solve the following system of imequalities: 2x+3y-4>0 3x-4y+5>0
  37. D

    Equations of motion of a system with non holonomic constraints

    Hello, I have a system with 2 degrees of freedom with 2 non-holonomic constrains that can be expressed by:##A_1 dq_1 +Cdq_3 + Ddq_4 = 0## ##A_2 dq_1 + Bdq_2 = 0##Being ##q_1, q_2, q_3## and ##q_4## four generalized coordinates that can describe the movement of the system. And ##A_1, A_2, B...
  38. Boyles

    Internal forces acting on a dive system

    Hello please be aware that my understanding of physics is basic, but I want to learn - and I will if explained simply enough please. I looked on here and found the cube in space query from last year, and I just about understood it, but the scalars and vectors did throw me, so hopefully it will...
  39. Z

    A How Do You Determine the Mapping Functions in a Curvilinear Coordinate System?

    Hello, the physical domain in the (y, z) space is mapped to a rectangular computational region in the (ŋ,Ƹ)-space, where (ŋ,Ƹ) are the new coordinates. This technique frees the computational simulation from geometry restriction. after transforming the governing equations ( PDEs) to the...
  40. leticia beira

    The figure represents a system composed of pulleys

    The figure represents a system composed of two ideal fixed pulleys that support three masses A, B, and C of the same mass M, suspended by light and inextensible threads. Massor A is simultaneously suspended by two wires, one connected to massor B (wire 1) and the other to massor C (wire 2). We...
  41. I

    Forces acting on a support point after the system is released

    Summary:: What is the force N which acts on a support point at the moment just after system is released? [Thread moved from the technical forums, so no Homework Template is shown] A light bar with m1 and m2 masses (m1≠m2) at the ends placed on the support point (in the middle of the bar)...
  42. K

    Projectile-car system and momentum

    I have done question 1. But I'm struggling with the other one. So since the only thing I know about the rocket is the mass and the velocity, I guess I have to use momentum to solve this problem. From the first question, I found out that the x-velocity of the projectile is ##v_x=5...
  43. J

    I Falling EM system contradicts the equivalence principle?

    The following is an improved version of my previous post https://www.physicsforums.com/threads/falling-electric-dipole-contradicts-the-equivalence-principle.964594/ Consider the following system comprising a particle on the left with charge ##+q## that is a large distance ##d## away from two...
  44. cookiemnstr510510

    Sign conventions for work done by/on a system

    I am a bit confused on the definition/convention of work. In some books I see statements that say : "If work is done on the system, its sign is positive. If work is done by the system, its sign is negative." And in other books I see things like: "By convention, work is regarded as positive...
  45. anemone

    MHB System of Equations: Find Triples $(x,y,z)$

    Find all triples $(x,\,y,\,z)$ of real numbers that satisfy the system of equations $x^3=3x-12y+50\\y^3=12y+3z-2\\z^3=27z+27x$
  46. D

    Question about the solution of this system of equations

    hi given such system of equations ## \begin{cases} \rho^2 = 2 \rho \\ 2\theta= -\theta+2k\pi , k\in \mathbb Z \\ \end{cases} ## in the solution of the professor the system is solved is solved as follows. ## \begin{cases} \rho=0 , \rho=2 \\ \theta= -\frac 2 3 k\pi , k = 0,1,2 \\...
  47. M

    Suggest a geometry for headphone's speaker system

    Summary:: Suggest a geometry Hello! I have difficulties with this question. It is translated from Swedish so if something's weird tell me. The speakers in headphones often work with the help of magnetism, when a varying voltage is applied across a coil attached to the speaker membrane. The...
  48. B

    Pressure loss pipe system: Conversion from known fluid1 to fluid2

    Hello, everyone, I am currently working on the following (real) problem, where I am not getting anywhere. It would be super nice if you could have a look at this. Thank you very much :-). I have a pipe system (Black Box) of which I only know the following things: At a set flow rate with a...
  49. jisbon

    Engineering Finding the system output by convolution

    Since there are initial conditions stated, I would have to craft the s equation in mind, in order to find the impulse by laplace inverse; which is this: ##(s^2Y(s)-sy(0)-y'(0))+8(sY(s)-y(0))+16Y(s)=x(s)## ##(s^2Y(s)+\frac{1}{2}s-1)+8(sY(s)-1)+16Y(s)=x(s)##...
  50. R

    Why gravitational potential energy is a system property?

    Spring has more potential energy when it is compressed or stretched from its initially balanced state. As external work is done, it stores energy in the form of potential energy. Here, we know energy is stored in spring but For the Earth-ball system, where the energy stored?
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