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  2. Planck constant - Wikipedia

    en.wikipedia.org/wiki/Planck_constant

    This value is used to define the SI unit of mass, the kilogram: "the kilogram [...] is defined by taking the fixed numerical value of h to be 6.626 070 15 × 10 −34 when expressed in the unit J⋅s, which is equal to kg⋅m 2 ⋅s −1, where the metre and the second are defined in terms of speed of light c and duration of hyperfine ...

  3. Action (physics) - Wikipedia

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

    The action is defined by an integral, and the classical equations of motion of a system can be derived by minimizing the value of that integral. The action principle provides deep insights into physics, and is an important concept in modern theoretical physics. Various action principles and related concepts are summarized below.

  4. Energy conversion efficiency - Wikipedia

    en.wikipedia.org/wiki/Energy_conversion_efficiency

    6–40% (technology-dependent, 15–20% most often, median degradation for x-Si technologies in the 0.5–0.6%/year [20] range with the mean in the 0.8–0.9%/year range. Hetero-interface technology (HIT) and microcrystalline silicon (μc-Si) technologies, although not as plentiful, exhibit degradation around 1%/year and resemble thin-film ...

  5. Duty cycle - Wikipedia

    en.wikipedia.org/wiki/Duty_cycle

    In electronics, duty cycle is the percentage of the ratio of pulse duration, or pulse width (PW) to the total period (T) of the waveform. It is generally used to represent time duration of a pulse when it is high (1).

  6. Percentage - Wikipedia

    en.wikipedia.org/wiki/Percentage

    The percent value is computed by multiplying the numeric value of the ratio by 100. For example, to find 50 apples as a percentage of 1,250 apples, one first computes the ratio ⁠ 50 / 1250 ⁠ = 0.04, and then multiplies by 100 to obtain 4%. The percent value can also be found by multiplying first instead of later, so in this example, the 50 ...

  7. Relativistic rocket - Wikipedia

    en.wikipedia.org/wiki/Relativistic_rocket

    At 30% c, the difference between relativistic mass and rest mass is only about 5%, while at 50% it is 15%, (at 0.75c the difference is over 50%); so above such speeds special relativity is needed to accurately describe motion, while below this range Newtonian physics and the Tsiolkovsky rocket equation usually give sufficient accuracy.

  8. Relative change - Wikipedia

    en.wikipedia.org/wiki/Relative_change

    A percentage change is a way to express a change in a variable. It represents the relative change between the old value and the new one. [6]For example, if a house is worth $100,000 today and the year after its value goes up to $110,000, the percentage change of its value can be expressed as = = %.

  9. Stefan–Boltzmann law - Wikipedia

    en.wikipedia.org/wiki/Stefan–Boltzmann_law

    The temperature Stefan obtained was a median value of previous ones, 1950 °C and the absolute thermodynamic one 2200 K. As 2.57 4 = 43.5, it follows from the law that the temperature of the Sun is 2.57 times greater than the temperature of the lamella, so Stefan got a value of 5430 °C or 5700 K. This was the first sensible value for the ...