MKSA?

 

In addition to the MKSA (meter-kilogram-second-ampere) system, which is a subset of the International System of Units (SI), there are several other systems used in science:

1. CGS System (Centimeter-Gram-Second):
• Units: Centimeter (cm) for length, Gram (g) for mass, Second (s) for time.
• Common in: Electromagnetism and theoretical physics.
• Variants: Gaussian units, ESU (Electrostatic units), EMU (Electromagnetic units).
2. FPS System (Foot-Pound-Second):
• Units: Foot (ft) for length, Pound (lb) for mass, Second (s) for time.
• Common in: Engineering and some older scientific contexts.
• Variants: British Imperial system, US customary system.
3. Natural Units:
• Units: Based on universal physical constants (e.g., Planck units).
• Common in: Theoretical physics and cosmology.
• Examples: Planck length, Planck time, Planck mass.
4. Astronomical Units:
• Units: Based on celestial measurements.
• Common in: Astronomy and astrophysics.
• Examples: Astronomical unit (AU) for distance, Solar mass (M☉) for mass, Light-year (ly) for distance, Parsec (pc) for distance.
5. Imperial System:
• Units: Inch, foot, yard for length; ounce, pound, ton for mass; second for time.
• Common in: Primarily used in the United States and a few other countries.
6. Biochemical and Medical Units:
• Units: Used specifically in biochemistry and medicine.
• Examples: Daltons (Da) for atomic mass, milliliters (mL) for volume, International Units (IU) for measuring biological activity.
7. Thermodynamic Units:
• Units: Specific to thermodynamics.
• Examples: Calorie (cal), British thermal unit (BTU), Kelvin (K), Joule (J).
8. Atomic Units:
• Units: Based on atomic scales.
• Common in: Atomic physics and quantum mechanics.
• Examples: Atomic unit of length (Bohr radius), atomic unit of energy (Hartree).

These systems have evolved to meet the needs of various scientific disciplines, providing convenient units for measuring and calculating physical quantities within specific contexts.

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