isolated system

(noun)

A system that does not interact with its surroundings, that is, its total energy and mass stay constant.

Related Terms

Examples of isolated system in the following topics:

  • Conservation of Mechanical Energy

    • Conservation of mechanical energy states that the mechanical energy of an isolated system remains constant without friction.
    • Conservation of mechanical energy states that the mechanical energy of an isolated system remains constant in time, as long as the system is free of all frictional forces.
    • An example of a such a system is shown in .
    • Though energy cannot be created nor destroyed in an isolated system, it can be internally converted to any other form of energy.
    • The total kinetic plus potential energy of a system is defined to be its mechanical energy (KE+PE).

  • Internal Energy

    • The internal energy of a system is the sum of all kinetic and potential energy in a system.
    • However, a system does contain a quantifiable amount of energy called the internal energy of a system.
    • At any finite temperature, kinetic and potential energies are constantly converted into each other, but the total energy remains constant in an isolated system.
    • Q is heat added to a system and Wmech is the mechanical work performed by the surroundings due to pressure or volume changes in the system.
    • We can calculate a small change in internal energy of the system by considering the infinitesimal amount of heat δQ added to the system minus the infinitesimal amount of work δW done by the system:

  • The First Law

    • The 1st law of thermodynamics states that internal energy change of a system equals net heat transfer minus net work done by the system.
    • It is usually formulated by stating that the change in the internal energy of a closed system is equal to the amount of heat supplied to the system, minus the amount of work done by the system on its surroundings.
    • The law of conservation of energy can be stated like this: The energy of an isolated system is constant.
    • Here ΔU is the change in internal energy U of the system, Q is the net heat transferred into the system, and W is the net work done by the system.
    • So positive Q adds energy to the system and positive W takes energy from the system.

  • Internal vs. External Forces

    • Newton's 2nd law, applied to an isolated system composed of particles, $\bf{F}_{tot} = \frac{d\bf{p}_{tot}}{dt} = 0$ indicates that the total momentum of the entire system $\bf{p}_{tot}$ should be constant in the absence of net external forces.
    • Let's first list all the forces present in the system.
    • How should we define our system?
    • Total momentum of the system (or Cradle) is conserved.
    • (neglecting frictional loss in the system. )

  • Global Warming Revisited

    • This brings up two important points: optimized heat sinks are at absolute zero, and the longer engines dump heat into an isolated system the less efficient engines will become.

  • Constant Pressure and Volume

    • An example would be to have a movable piston in a cylinder, so that the pressure inside the cylinder is always at atmospheric pressure, although it is isolated from the atmosphere.
    • In other words, the system is dynamically connected, by a movable boundary, to a constant-pressure reservoir.
    • If a gas is to expand at a constant pressure, heat should be transferred into the system at a certain rate.
    • It follows that, for the simple system of two dimensions, any heat energy transferred to the system externally will be absorbed as internal energy.
    • We may say that the system is dynamically insulated, by a rigid boundary, from the environment.

  • Electric Activity in the Heart

    • In the atria the electrical signal moves from cell to cell (see section on nerve conduction and the electrocardiogram) while in the ventricles the signal is carried by specialized tissue called the Purkinje fibers which then transmit the electric charge to the myocardium. shows the isolated heart conduction system.
    • If the SA node does not function, or the impulse generated in the SA node is blocked before it travels down the electrical conduction system, a group of cells further down the heart will become the heart's pacemaker.
    • Purkinje fibers allow the heart's conduction system to create synchronized contractions of its ventricles, and are therefore essential for maintaining a consistent heart rhythm.

  • Conservation of Angular Momentum

    • A closed system is involved.
    • They are isolated from rotation changing influences (hence the term "closed system").
    • There appears to be a numerical quantity for measuring rotational motion such that the total amount of that quantity remains constant in a closed system.

  • Electric Field and Changing Electric Potential

    • Placing a second charge in the system (a "test charge") results in the two charges experiencing a force (the field's units are Newtons, a measure of force per Coulomb), causing the charges to move relative to one another.
    • An isolated point charge Q with its electric field lines (blue) and equipotential lines (green)

  • Linear Dependence and Independence

    • If this is true with at least one of the coefficients $\alpha _ i$ nonzero, then we could isolate a particular vector on the right hand side, expressing it as a linear combination of the other vectors.
    • As a result, if we are faced with a linear system of equations to solve