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. F

    Calculating Work Done on a Basketball Dropped from 5m

    Homework Statement A basketball with a mass of 0.56 kg drops from a height of 5 m and bounces off the floor back up to a maximum height of 4.3 m .Find the work done on the ball by the ground during the time the ball is in contact with it. Homework Equations W = - Δ Ug Ug = mgh The Attempt at a...
  2. M

    MHB Solving a system of multivariable equations

    Consider the equation system x*e^y + y*f(z) = a x*g(x,y) +z^2 = b where f(z) and g(x,y) are differentiable functions, and a and b are constants. Suppose that the system defines x and y as differentiable functions of z. Find expressions for dx/dz and dy/dz. Any help would be appreciated...
  3. W

    I Why this system has a rotational symmetry in Dirac equation?

    why system has a rotational symmetry in dirac equation? is that a general property of all systems?
  4. F

    Energy of System: Which Statement is Always Correct?

    Homework Statement Which of the following statements is always correct? A) The work of friction force is negative. B) The work of gravity is positive C)The work of the spring is negative D) The work of the normal force is negative E) None of the above The Attempt at a Solution My answer is E...
  5. Spinnor

    B New theory, our solar system formation, "space bubble"

    "There are various theories about how the solar system formed, but scientists haven't been able to agree on a single model that explains all the quirks of our corner of space as it exists today. Now, scientists at the University of Chicago have...
  6. G

    'Alien' biosphere immune system effects

    Hello, Suppose we humans traveled in a spacecraft to another Earth like planet with the same gravity and atmospheric composition as our own Earth. Suppose we landed on the surface. Suppose we opened the door of the craft, and walked onto the planet surface. Suppose we did not wear a...
  7. N

    My Plug And Play Solar Energy System

    Hi everyone, i'd like to share my packaged (plug and play) solar system project that I assembled at home. I used mostly standard parts such as a charge controller, inverter, 12 Volt UPS battery, and a pair of NEMA 5-15 R power outlets. I built the automatic transfer switch and battery...
  8. M

    Work done by the system, positive or negative?

    My chemistry course says that work done by the system is negative, but physics course says that work done by the system is positive, I'm sure I'm missing something and I really need to understand it. Thanks.
  9. K

    Block-pulley system and rotational dynamics

    Homework Statement Two blocks, m1 = 1.0 kg and m2 = 2.0 kg are connected by a light string as shown in the figure. If the radius of the pulley is 1.0 m and its moment of inertia is of the system is 5.0 kg*m^2, the acceleration of the system is (expressed as a fraction of gravitational...
  10. K

    Block-pulley system and kinetic energy

    Homework Statement A pulley with a radius of 3.0 cm and a rotational inertia of 4.5×10^-3 kg·m2 is suspended from the ceiling. A rope passes over it with a 2.0-kg block attached to one end and a 4.0-kg block attached to the other. The rope does not slip on the pulley. At any instant after the...
  11. C

    Which Type of Geothermal Power System is the Best?

    There are three geothermal systems that are commonly used: sry steam, flash steam, and binary cycle https://www.eia.gov/energyexplained/index.cfm?page=geothermal_power_plants . What are the efficiencies of the plants from best to least effecient on average?
  12. Dr Eve Wildman

    A AC transport data query (using a PPMS system)

    Hello and thanks for looking at this question. I have a semi-conducting sample which has been run on a PPMS system - measuring it's resistivity as a function of temperature. I switched to AC transport mode in order to measure the resistivity again while applying frequencies between 1Hz -...
  13. Duke Le

    I [Signal and system] Function with fourier series a[k] = 1

    We have: Period T = 4, so fundamental frequency w0 = pi/2. This question seems sooo easy. But when I use the integral: x(t) = Σa[k] * exp(i*k*pi/2*t). I get 1 + sum(cos(k*pi/2*t)), which does not converge. Where did I went wrong ? Thanks a lot for your help.
  14. M

    Change in temperature for a system with entropy change

    Homework Statement I am Pretty Lost with this problem...[/B] A 2.45-kg aluminum pan at 155∘C is plunged into 3.58 kg of water. If the entropy change of the system is 162 J/K, what was the initial temperature of the water? NOTE:We did not receive a Tf for the system. Homework Equations...
  15. Y

    I Angular momentum state of a system

    Hello, Suppose that the angular momentum of a system can take the values 0, 1, 2. One carries out a measurement of ##J_z## on this system. What can be said about the state of the system after the measurement? To what extent can it be perfectly certain if ##J_y## and ##J_x## do not commutate...
  16. S

    Can subharmonics in a system be also termed as bifurcation?

    I think that the existence of subharmonics is also bifurcation.Is that true
  17. Jayalk97

    Solving for the impulse response of a discrete time system?

    Hey guys I was just studying for finals and I came across something in my textbook that either wasn't explained properly or something I just don't get. So this page explains that the coefficient of y_n[k] is A_0, which is represented by b_0/a_0, I can see that a_0 is determined by multiplying...
  18. H

    Inertia of System: Find w/ Pink Dot & Diagonals

    Hi, in the following problem, I need to find the inertia of the system. The axis of rotation passes through the center of mass ( the pink dot). I understand that I will be equal to 4(mr^2). However, I do not understand why r= 3 (6 divided by 2) and not sqrt13 ( half of the diagonal of the...
  19. J

    Compensator Design in system control

    Hello, in my final project for System Control i have been stuck for some time on this following task What i cannot figure out is how to make all these condition work at the same time. When I tried designing a PD controller in sisotool or MATLAB for the i and ii part it worked but i couldn't...
  20. jalalapeno

    Finding Tension and theta in a pulley system

    What I've attempted to do is resolve vertically and horizontally: T1sin(30)+T2sinΘ+T2=9g T2cosΘ=T1cos30 After that... I'm completely stuck. Any help would be appreciated, I've spent so long on this I bet I'm just missing one simple thing. Thanks in advance
  21. J

    Control System: Find the Transfer Function From Block Diagram

    Homework Statement Homework Equations To find Ca / Rb we take Ra = 0 --- is this right? I used mason's formula P1 = -G2 G1 H1 Loop = G1, G2, -H1, -H2 Using Mason's Gain we get: Delta1 = 1 Delta = 1 - G1G2H1H2 Using Mason's Gain TF = -G1G2H1 Divided by ( 1 - G1G2H1H2) But substituting the...
  22. S

    Finding the total momentum of system

    Homework Statement A car of mass 1500 kg is at rest on a platform of mass 3000 kg, which is also at rest. The platform has frictionless wheels attached to its bottom. The whole system is initially at rest. The car starts to move forward at a speed of 5.0 m/s with respect to the ground...
  23. B

    B Exploring Physical Life in the Sirius Star System

    Can the Sirius star system support physical life in any way including those that can breath carbon dioxide or other gases?
  24. vibhuav

    I Evaluating metric tensor in a primed coordinate system

    I am trying to learn GR. In two of the books on tensors, there is an example of evaluating the inertia tensor in a primed coordinate system (for example, a rotated one) from that in an unprimed coordinate system using the eqn. ##I’ = R I R^{-1}## where R is the transformation matrix and...
  25. P

    Construct the Lagrangian for the system

    Homework Statement Hello! I have some problems with constructing Lagrangian for the given system: (Attached files) Homework Equations The answer should be given in the following form: L=T-U=... The Attempt at a Solution I tried to construct the Lagrangian, but I'm not sure if I did it...
  26. J

    Fluid Velocity and Pressure in a *Closed* System

    In a closed fluidic system (with a pump), fluid velocity is constant throughout the system but what puzzles me is the pressure drop due to viscous effect. In a horizontal pipe, pressure decreases gradually (assuming low friction) down the pipe due to viscous effect. In this concepts, it's hard...
  27. P

    Determining the power of a rotating system

    Homework Statement Force of 200 foot pounds of torque is being exerted on a axle of a disc which is turning at 1.57 radians. The disk has a moment of inertia of 234 kg per meter squared and it's 1.5 inch diameter axle has a prony brake installed applying a load of 200 foot pounds of torque at...
  28. VSayantan

    Entropy of a System of Spin-half Non-interacting Particles

    Homework Statement A system having ##N## non-degenerate energy eigenstates populated by##N## identical spin-zero particles and ##2N## identical spin-half particles. There are no interaction between any of these particles. If ##N=1000## what is the entropy of the system? Homework Equations...
  29. S

    I Consequences on a system of ODEs after performing operations

    Hi, I have derived a matrix from a system of ODE, and the matrix looked pretty bad at first. Then recently, I tried the Gauss elimination, followed by the exponential application on the matrix (e^[A]) and after another Gauss elimination, it turned "down" to the Identity matrix. This is awfully...
  30. M

    Isentropic Expansion Within a Steam Turbine System

    Homework Statement Steam is expanded from 90 bar, 412°C to 4.0 bar saturation in a high pressure turbine, after-which a certain percentage of the steam is bled off to a feed heater. The remaining steam is then expanded through a low pressure turbine to 1.0 bar and dryness fraction of 0.93. All...
  31. MacLaddy

    Pressure loss in an HVAC system

    I'm working on my first engineering project in the real-world and I'm hitting a bit of a snag. It's regarding pressure loss analysis in an HVAC system. We have a system that is capable of providing a maximum of 2.0-in.wg pressure at the air handler, but we are finding very little air movement at...
  32. Francis Hannah

    Resultant force-couple system where resultant couple is 0

    For the structure, find the distance from O (in direction OA) to the point where the resultant force-couple system of the forces shown should have a resultant couple of zero. Give answer in metres. a=90 N, b=289 N, c=549 N Clockwise negative, anticlockwise positive. Moment at a =...
  33. J

    MHB Complex Variables - Solution of a System

    Suppose the polynomial p has all its zeros in the closed half-plane $Re w\le0$, and any zeros that lie on the imaginary axis are of order one. $$p(z)=det(zI-A),$$ where I is the n x n identity matrix. Show that any solution of the system $$\dot{x}=Ax+b$$ remains bounded as $t\to{\infty}$...
  34. R

    Comp Sci Velocity Verlet applied to solar system with C++

    Homework Statement Hello, I am attempting to use the velocity Verlet algorithm of integration applied to the solar system in c++. My goal is be able to use the outputted position components in a plot to see if the trajectory of my object is elliptical/parabolic/hyperbolic resulting from the...
  35. B

    Derive a wave equation for an n mass coupled system

    1. Derive the wave equation for longitudinal vibrations in an extended 1-D system of masses and springs. The average distance between masses is D [m], the spring constants are K [kg/s2 ], and the masses are M [kg]. b) Determine the wave speed c as a function of D, K, and M. Verify that it has...
  36. D

    Center of mass system of two interacting identical Fermions

    Homework Statement Consider the center of mass system of two interacting fermions with spin 1/2. a) What is the consequence of the Pauli exclusion principle on the two-particle wave function? b)Let S1 and S2 be the spin operators of the two individual fermions. Show that the operators...
  37. VSayantan

    Free Energy of a Simple Quantum System

    Homework Statement [/B]A quantum system has three energy levels, ##-0.12 ~\rm{eV}##, ##-0.20 ~\rm{eV}## and ##-0.44 ~\rm{eV}## respectively. Three electrons are distributed among these three levels. At a temperature of ##1727^o \rm{C}## the system has total energy ##-0.68 ~\rm{eV}##. What is...
  38. thepikminman

    Vibrations - Modeling system, equation of motion

    Vibrations - Modelling system, equation of motion Hi, In the first question (question 4) in the attached file, how would you go about modelling the system and finding the equation of motion? All those masses are confusing me, I don't even know where to start. I don't know whether the angle...
  39. S

    Solving for Final Equilibrium Temperature of Water-Copper System

    Homework Statement 173 g of water at 20°C is contained in a copper container of mass 327 g. An additional 129 g of water at 100°C is added. What is the final equilibrium temperature (in degrees C) if we treat the system's water and container as isolated? Homework Equations Q = mcΔT The...
  40. T

    I Where in our solar system are asteroids that contain ammonia

    Hi! I'm doing a research project titled "Is it possible to colonise Mars?" I'm currently researching how to raise the temperature and pressure - and I've discovered to do this that re-directing asteroids towards Mars containing Ammonia would be vital. However, where do these asteroids that...
  41. R

    Modes of Vibration of 3-DOF Spring Mass System

    Homework Statement Homework Equations a11 = a21 = a31 = a12 = a13 a22 = a32 = a23 $$ \begin{bmatrix} x_{1} \\ x_{2} \\ x_{3} \end{bmatrix} =ω^2m \begin{bmatrix} a_{11} & a_{12} & a_{13} \\ a_{21} & a_{22} & a_{23} \\ a_{31} & a_{32} & a_{33}...
  42. M

    Solve the system of equations?

    Homework Statement Solve the system of equations x1-3x2-2x3=0 -x1+2x2+x3=0 2x1+4x2+6x3=0 using either Gaussian or Gauss-Jordan elimination. Homework Equations None. The Attempt at a Solution R1+R2, I got x1-3x2-2x3=0 -x2-x3=0 2x1+4x2+6x3=0...
  43. I

    Automotive Compound Epicyclical gear system

    Trying to calculate how to produce a 1:12 ratio gear train with epicyclical gears. Can anyone send some equations or links to help explain how to do this? I have looked in textbooks and online and found many examples of achieving this with a simple compound spur gear train with 3 or less stages...
  44. pairofstrings

    Operating system concepts in an app by Linux System calls

    Before I begin learning what System Calls, Kernel, and Operating System is, I want to confirm that Operating System concepts like Multi-threading, Concurrency, Parallelism, Scheduling, Memory Management, Process Management, Network Management, Device Drivers can be implemented by using Linux...
  45. C

    MHB Angular power for a system

    A sphere of mass 1.9 kg and radius 0.5 m is attached to the end of a massless rod of length 3.0 m. The rod rotates about an axis that is at the opposite end of the sphere (see below). The system rotates horizontally about the axis at a constant 422 rev/min. After rotating at this angular speed...
  46. T

    I How to identify if a system exhibits chaos?

    How to tell if a non linear equation exhibits chaos? Sorry, I am a beginner on this topic. And my library doesn't have book on this topic. I only read about this from John R Taylor's Mechanics book. I am looking for further resources. TIA
  47. P

    I Magnetic field of Solar System planets

    Hello. I am reading a paper which says that only Earth (between the rocky planets) keep a strong magnetic field and it arose an question on this: Why does the magnetic field of the planets decrease with time in such planets? Why the magnetic field of the Earth is the only one which keeps strong?
  48. D

    MHB Sensitivity Analysis model for omnivory systems (coupled system of ode's)

    \chapter{Stage Structured Omnivory Model} %\indent For our initial computations we will be using a standard Lotka-Volterra omnivory model which was developed to analyze the population and community level dynamics. The model depicted below (figure 1.4) is a standard Lotka-Volterra model of...
  49. J

    Unsure Regarding Temperature Model for an Open System

    Hi guys, I am currently working on my master thesis. I am supposed to make a dynamic model for a gas system and have some trouble setting up the energy balance. I am a noob when it comes to uploading pictures, so I don't have a figure for this, but let's consider a general control volume (CV)...
  50. I

    Compressed Air Energy Storage System

    Homework Statement I have a CAES system that takes air at a pressure of 102.2kPa and temp of 24 degrees C. It is compressed to 85 bar adiabatically at a rate of 168 kg/s. I know that Cp = 1.005 kJ/kgK and Cv = 0.718 kJ/kgK. The question is - determine the amount of work consumed by the...
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