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  2. Time in physics - Wikipedia

    en.wikipedia.org/wiki/Time_in_physics

    In the International System of Units (SI), the unit of time is the second (symbol: s). It has been defined since 1967 as "the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom", and is an SI base unit. [12]

  3. Continuum limit - Wikipedia

    en.wikipedia.org/wiki/Continuum_limit

    An animated example of a Brownian motion-like random walk on a torus.In the scaling limit, random walk approaches the Wiener process according to Donsker's theorem.. In mathematical physics and mathematics, the continuum limit or scaling limit of a lattice model characterizes its behaviour in the limit as the lattice spacing goes to zero.

  4. Limit cycle - Wikipedia

    en.wikipedia.org/wiki/Limit_cycle

    Stable limit cycle (shown in bold) and two other trajectories spiraling into it Stable limit cycle (shown in bold) for the Van der Pol oscillator. In mathematics, in the study of dynamical systems with two-dimensional phase space, a limit cycle is a closed trajectory in phase space having the property that at least one other trajectory spirals into it either as time approaches infinity or as ...

  5. Jerk (physics) - Wikipedia

    en.wikipedia.org/wiki/Jerk_(physics)

    Lower deceleration limit — zero jerk; linear decrease in velocity; Deceleration ramp down — positive jerk limit; linear increase in acceleration to zero; quadratic decrease in velocity; approaching the desired position at zero speed and zero acceleration; Segment four's time period (constant velocity) varies with distance between the two ...

  6. Time constant - Wikipedia

    en.wikipedia.org/wiki/Time_constant

    In an increasing system, the time constant is the time for the system's step response to reach 1 − 1 / e ≈ 63.2% of its final (asymptotic) value (say from a step increase). In radioactive decay the time constant is related to the decay constant (λ), and it represents both the mean lifetime of a decaying system (such as an atom) before it ...

  7. Entropy as an arrow of time - Wikipedia

    en.wikipedia.org/wiki/Entropy_as_an_arrow_of_time

    Thus, for example, if Q was 50 units, T 1 was initially 100 degrees, and T 2 was 1 degree, then the entropy change for this process would be 49.5. Hence, entropy increased for this process, the process took a certain amount of "time", and one can correlate entropy increase with the passage of time.

  8. Thermodynamic limit - Wikipedia

    en.wikipedia.org/wiki/Thermodynamic_limit

    The thermodynamic limit is essentially a consequence of the central limit theorem of probability theory. The internal energy of a gas of N molecules is the sum of order N contributions, each of which is approximately independent, and so the central limit theorem predicts that the ratio of the size of the fluctuations to the mean is of order 1/N 1/2.

  9. Time derivative - Wikipedia

    en.wikipedia.org/wiki/Time_derivative

    Many other fundamental quantities in science are time derivatives of one another: force is the time derivative of momentum; power is the time derivative of energy; electric current is the time derivative of electric charge; and so on. A common occurrence in physics is the time derivative of a vector, such as velocity or displacement. In dealing ...