Absolute meter-tonne-second system
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The absolute meter-tonne-second system is a system of mechanical units. The meter is the base unit of length or distance, the tonne is chosen to be a unit of mass, and the second is the base unit of time. All other mechanical quantities, and specifically force, are expressed in terms of combinations of these three units. In absolute systems, Newton's second law is expressed as F = ma, and since acceleration is the second derivative of a distance with respect to time, if the unit of length or distance is denoted by L, the unit of mass by M, and the unit of time by T, the unit of force becomes a derived unit of dimensions MLT^{−2}, in this case tonne·metersecond^{2}, which is known as the sthène.
Base |
force, length, time | weight, length, time | mass, length, time | |||||
---|---|---|---|---|---|---|---|---|
Force (F) | F = m·a = w·ag | F = m·ag_{c} = w·ag | F = m·a = w·ag | |||||
Weight (w) | w = m·g | w = m·gg_{c} ≈ m | w = m·g | |||||
System | BG | GM | EE | M | AE | CGS | MTS | SI |
Acceleration (a) | ft/s^{2} | m/s^{2} | ft/s^{2} | m/s^{2} | ft/s^{2} | gal | m/s^{2} | m/s^{2} |
Mass (m) | slug | hyl, also called “metric slug” or “TME” | lb_{m} | kg | lb | g | t | kg |
Force (F) | lb | kp | lb_{F} | kp | pdl | dyn | sn | N |
Pressure (p) | lb/in^{2} | at | PSI | atm | pdl/ft^{2} | Ba | pz | Pa |
DetailsEdit
The meter-tonne-second or mts system of units is a system of physical units. It was invented in France, hence the unit names sthène and pièze, and was adopted only by the Soviet Union in 1933, and abolished there in 1955. It was a coherent system of units, much as SI and the cgs system, but with larger units for industrial use. The cgs system on the other hand was regarded as suitable for laboratory use only.^{[3]}^{[4]}
Units Edit
The base units of the mts system are as follows:
- length: meter
- volume: cubic meter
- 1 m^{3} ≡ 1kL
- mass: tonne,
- 1 t ≡ 10^{3} kg
- time: second
- force: sthène,
- 1 sn ≡ 1 t·m/s^{2} = 10^{3} N = 1 kN
- energy: sthène-meter = kilojoule,
- 1 sn·m ≡ 1 t·m^{2}/s^{2} = 10^{3} J = 1 kJ
- power: sthène-meter per second = kilowatt,
- 1 sn·m/s ≡ 1 t·m^{2}/s^{3} = 10^{3} W = 1 kW
- pressure: pièze,
- 1 pz ≡ 1 t/m·s^{2} = 10^{3} Pa = 1 kPa = 1 centibar (cbar)
ReferencesEdit
- ↑ Lindeburg, Michael, Civil Engineering Reference Manual for the PE Exam
- ↑ Wurbs, Ralph A, Fort Hood Review Sessions for Professional Engineering Exam, http://engineeringregistration.tamu.edu/tapedreviews/Fluids-PE/PDF/Fluids-PE.pdf, retrieved October 26, 2011
- ↑ "System of Measurement Units". IEEE Global History Network. Institute of Electrical and Electronics Engineers (IEEE). http://www.ieeeghn.org/wiki/index.php/System_of_Measurement_Units. Retrieved 2011-03-21.
- ↑ "Notions de physique - Systèmes d'unités [Symbols used in physics - units of measure]" (in French). Hydrelect.info. http://www.hydrelect.info/articles.php?lng=fr&pg=3. Retrieved 2011-03-21.