Check That You Have Converted Between Si Units Correctly. No Credit Lost. Try Again.
SI Unit of measurement rules and fashion conventions
Cheque List for
![]() | |||||||||||||||||||||||||||||
#1![]() | Merely units of the SI and those units recognized for use with the SI are used to express the values of quantities. Equivalent values in other units are given in parentheses post-obit values in acceptable units only when deemed necessary for the intended audition. | ||||||||||||||||||||||||||||
![]() | |||||||||||||||||||||||||||||
#ii![]() | Abbreviations such as sec, cc, or mps are avoided and but standard unit symbols, prefix symbols, unit names, and prefix names are used. | ||||||||||||||||||||||||||||
proper: | s or second; cmiii or cubic centimeter; m/s or meter per second | ||||||||||||||||||||||||||||
improper: | sec; cc; mps | ||||||||||||||||||||||||||||
![]() | |||||||||||||||||||||||||||||
#3![]() | Unit of measurement symbols are unaltered in the plural. | ||||||||||||||||||||||||||||
proper: | l = 75 cm | ||||||||||||||||||||||||||||
improper: | l = 75 cms | ||||||||||||||||||||||||||||
![]() | |||||||||||||||||||||||||||||
#4![]() | Unit of measurement symbols are not followed by a period unless at the finish of a judgement. | ||||||||||||||||||||||||||||
proper: | The length of the bar is 75 cm. The bar is 75 cm long. | ||||||||||||||||||||||||||||
improper: | The bar is 75 cm. long. | ||||||||||||||||||||||||||||
![]() | |||||||||||||||||||||||||||||
#5![]() & partition | A infinite or one-half-high dot is used to signify the multiplication of units. A solidus (i.e., slash), horizontal line, or negative exponent is used to signify the division of units. The solidus must not exist repeated on the same line unless parentheses are used. | ||||||||||||||||||||||||||||
proper: | The speed of sound is most 344 grand·s-one (meters per second) The disuse rate of 113Cs is about 21 ms-one (reciprocal milliseconds) m/s, m·s-2, m·kg/(southiii·A), thou·kg·s-3·A-1 grand/southward, 1000 s-ii, m kg/(sthree A), m kg s-3 A-1 | ||||||||||||||||||||||||||||
improper: | The speed of sound is about 344 ms-1 (reciprocal milliseconds) The decay rate of 113Cs is about 21 thousand·s-1 (meters per 2d) m ÷ s, thou/due south/s, k·kg/south3/A | ||||||||||||||||||||||||||||
![]() | |||||||||||||||||||||||||||||
#half dozen![]() | Variables and quantity symbols are in italic type. Unit symbols are in roman type. Numbers should generally be written in roman type. These rules utilize irrespective of the typeface used in the surrounding text. For more details, meet Typefaces for symbols in scientific manuscripts | ||||||||||||||||||||||||||||
proper: | She exclaimed, " That dog weighs x kg ! " t = 3 due south, where t is time and s is second T = 22 K, where T is thermodynamic temperature, and M is kelvin | ||||||||||||||||||||||||||||
improper: | He exclaimed, " That dog weighs 10 kg! t = 3 s, where t is fourth dimension and southward is second T = 22 K, where T is thermodynamic temperature, and Grand is kelvin | ||||||||||||||||||||||||||||
![]() | |||||||||||||||||||||||||||||
#7![]() | Superscripts and subscripts are in italic type if they represent variables, quantities, or running numbers. They are in roman type if they are descriptive. | ||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||
![]() | |||||||||||||||||||||||||||||
#8![]() | The combinations of letters "ppm," "ppb," and "ppt," and the terms function per million, part per billion, and part per trillion, and the like, are not used to express the values of quantities. | ||||||||||||||||||||||||||||
proper: | two.0 µL/L; 2.0 ten 10-half-dozen Five; 4.3 nm/m; 4.iii ten ten-ix l; 7 ps/s; 7 x 10-12 t, where V, l, and t are the quantity symbols for volume, length, and time. | ||||||||||||||||||||||||||||
improper: | "ppm," "ppb," and "ppt," and the terms part per million, role per billion, and function per trillion, and the similar | ||||||||||||||||||||||||||||
![]() | |||||||||||||||||||||||||||||
#9![]() modifications | Unit symbols (or names) are not modified past the add-on of subscripts or other information. The post-obit forms, for example, are used instead. | ||||||||||||||||||||||||||||
proper: | V max = thou V a mass fraction of 10 % | ||||||||||||||||||||||||||||
improper: | 5 = 1000 Vmax 10 % (m/m) or 10 % (by weight) |
![]() | ||
#10![]() | The symbol % is used to stand for simply the number 0.01. | |
proper: | 50 1 = l 2(1 + 0.2 %), or D = 0.2 %, where D is defined by the relation D = (l one - l 2)/l ii. | |
improper: | the length l 1 exceeds the length l 2 past 0.ii % | |
![]() | ||
#11![]() & units | Information is not mixed with unit of measurement symbols or names. | |
proper: | the h2o content is 20 mL/kg | |
improper: | twenty mL H2O/ kg xx mL of water/ kg | |
![]() | ||
#12![]() notation | It is clear to which unit symbol a numerical value belongs and which mathematical operation applies to the value of a quantity. | |
proper: | 35 cm ten 48 cm 1 MHz to 10 MHz or (1 to 10) MHz 20 °C to 30 °C or (20 to 30) °C 123 grand ± 2 thousand or (123 ± 2) g lxx % ± 5 % or (70 ± 5) % 240 ten (1 ± 10 %) 5 | |
improper: | 35 x 48 cm 1 MHz-10 MHz or 1 to 10 MHz xx °C-30 °C or 20 to 30 °C 123 ± 2 g 70 ± 5 % 240 V ± 10 % (one cannot add 240 5 and 10 %) | |
![]() | ||
#13![]() symbols & names | Unit symbols and unit names are not mixed and mathematical operations are not applied to unit names. | |
proper: | kg/giii, kg · m-3, or kilogram per cubic meter | |
improper: | kilogram/miii, kg/cubic meter, kilogram/cubic meter, kg per thousand3, or kilogram per meter3. | |
![]() | ||
#14![]() unit symbols | Values of quantities are expressed in acceptable units using Standard arabic numerals and symbols for units. | |
proper: | m = 5 kg the current was 15 A | |
improper: | m = 5 kilograms m = five kg the current was 15 amperes | |
![]() | ||
#15![]() spacing | There is a space between the numerical value and unit symbol, even when the value is used in an adjectival sense, except in the example of superscript units for plane bending. | |
proper: | a 25 kg sphere an angle of 2° 3'four" If the spelled-out proper name of a unit is used, the normal rules of English use: "a roll of 35-millimeter film." | |
improper: | a 25-kg sphere an angle of ii ° 3 ' 4 " | |
![]() | ||
#16![]() spacing | The digits of numerical values having more than 4 digits on either side of the decimal marker are separated into groups of iii using a thin, fixed space counting from both the left and correct of the decimal marker. Commas are non used to separate digits into groups of three. | |
proper: | 15 739.012 53 | |
improper: | 15739.01253 15,739.012 53 | |
![]() | ||
#17![]() equations | Equations between quantities are used in preference to equations between numerical values, and symbols representing numerical values are different from symbols representing the corresponding quantities. When a numerical-value equation is used, it is properly written and the corresponding quantity equation is given where possible. | |
proper: | (50/m) = 3.6-ane [five/(km/h)](t/s) | |
improper: | l = 3.6-1vt, accompanied past text saying, "where l is in meters, five is in kilometers per hr, and t is in seconds" | |
![]() | ||
#xviii![]() symbols | Standardized quantity symbols are used. Similarly, standardized mathematical signs and symbols are used. More specifically, the base of "log" in equations is specified when required past writing | |
proper: | tan 10 R for resistance A r for relative diminutive mass | |
improper: | tg x for tangent of x words, acronyms, or advertisement hoc groups of letters | |
![]() | ||
#19![]() mass | When the give-and-take "weight" is used, the intended meaning is clear. (In science and technology, weight is a force, for which the SI unit is the newton; in commerce and everyday use, weight is usually a synonym for mass, for which the SI unit is the kilogram.) | |
![]() | ||
#20![]() quantity | A caliber quantity is written explicitly. | |
proper: | mass divided past volume | |
improper: | mass per unit of measurement volume | |
![]() | ||
#21![]() quantity | An object and any quantity describing the object are distinguished. (Note the difference betwixt "surface" and "area," "torso" and "mass," "resistor" and "resistance," "coil" and "inductance.") | |
proper: | A trunk of mass 5 g | |
improper: | A mass of five g | |
![]() | ||
#22![]() Terms | The obsolete terms normality, molarity, and molal and their symbols North, G , and m are not used. | |
proper: | amount-of-substance concentration of B (more commonly called concentration of B), and its symbol c B and SI unit mol/yard3 (or a related acceptable unit) | |
improper: | normality and the symbol North, molarity and the symbol M molal and the symbol m | |
![]() |
Return to Units home page
Online: February 1998 - Last update: September 2004
Source: https://physics.nist.gov/cuu/Units/checklist.html
0 Response to "Check That You Have Converted Between Si Units Correctly. No Credit Lost. Try Again."
Postar um comentário