## Forum archive 2000-2006

### Michael Gage - List of Units

by Arnold Pizer -
Number of replies: 0
 List of Units topic started 5/3/2000; 10:47:39 PMlast post 5/3/2000; 10:47:39 PM
Michael Gage - List of Units
5/3/2000; 10:47:39 PM (reads: 5806, responses: 0)
The answers you enter as the solutions to your WebWork problem sets must conform to the following conventions, in order to be interpreted and graded correctly.

## Problems requiring a numerical answer

Most answers consist of a numerical value followed by an abbreviation for the appropriate units of the physical quantity. A space must separate the numerical value from the units, as in for example 1.234 m.

### Numerical values

The numerical value may be written as a floating point decimal, for example 0.00314159, or in scientific notation as either 3.14159E-3 (as in FORTRAN) or 3.14159*10^-3 (with * signifying multiplication, and ^ signifying exponentiation; note in using the FORTRAN-like notation, you must use capital "E" and not small "e"). In place of a specific number for the numerical part of an answer, you may also use algebraic expressions. For example, (6+4)/2 is the same as writing 5. To see the syntax required for such expressions, as well as to see which special functions and numerical constants are recognized, see the section on Accepted math functions. Note that trigonometric functions assume the argument is expressed in radians and not degrees.

### Units

The units may be any compound expression of the form:

[unit]1^n1*[unit]2^n2*...*[unit]3^n3/ [unit]4^n4*[unit]5^n5*...*[unit]6^n6

where [unit]i is any of the unit abbreviations listed below, and the ni are positive or negative integers. The string of units before the / denote the numerator of the compound expression, while those following the / denote the denominator of the compound expression. There may be only one / in a given compound unit expression and no spaces are allowed within the units expression.

The abbreviations for units that are recognized by WebWork are:

 abbrev. unit name dimension equivalence in fundamental units FUNDAMENTAL MKS UNITS kg kilograms mass m meters length s seconds time OTHER BASIC UNITS deg degree angle 1 deg = pi/180 rad rad radian angle 1 rad = 180/pi deg ms millisecond time 1 ms = 0.001 s min minute time 1 min = 60 s hr hour time 1 hr = 60 min = 3600 s day day time 1 day = 24 hr = 8.64E4 s yr year time 1 yr = 365.25 day = 3.15576E7 s km kilometer length 1 km = 1000 m cm centimeter length 1 cm = 0.01 m mm millimeter length 1 mm = 0.001 m micron micrometer length 1 micron = 10^-6 m um micrometer length 1 um = 10^-6 m nm nanometer length 1 nm = 10^-9 m A Angstrom length 1 A = 10^-10 m in inch length 1 in = 0.0254 m ft feet length 1 ft = 12 in = 0.3048 m mi mile length 1 mi = 5280 ft = 1609.344 m light-year light year length 1 light-year = 9.46E15 m L liter volume 1 L = 10^-3 m^3 ml milliliter volume 1 ml = 10^-3 L = cm^3 cc cubic centimeter volume 1 cc = 10^-3 L = cm^3 knots nautical miles per hour velocity 1 knots = (1852/3600) m/s g gram mass 1 g = 10^-3 kg slug slug mass 1 slug = 14.6 kg Hz Hertz frequency 1 Hz = 1 s^-1 kHz kilo-Hertz frequency 1 kHz = 1000 Hz = 10^3 s^-1 MHz mega-Hertz frequency 1 MHz = 10^6 Hz = 10^6 s^-1 rev revolutions period 1 rev = 2pi rad cycles cycles period 1 cycles = 1 rev = 2pi rad degK degrees Kelvin temperature   degC degrees Centigrade temperature   degF degrees Fahrenheit temperature   COMPOUND UNITS N Newton force 1 N = 1 kg*m/s^2 microN micro-Newton force 1 microN = 10^-6 N = 10^-6 kg*m/s^2 uN micro-Newton force 1 uN = 10^-6 N = 10^-6 kg*m/s^2 J Joule energy 1 J = 1 N*m = 1 kg*m^2/s^2  kJ kilo-Joule energy 1 kJ = 1000 J = 10^3 kg*m^2/s^2  lbf foot-pound energy 1 lbf = 1.355 N*m = 1.355 kg*m^2/s^2 W Watt power 1 W = 1 J/s = 1 kg*m^2/s^3 kW kilo-Watt power 1 kW = 1000 W = 10^3 kg*m^2/s^3 dyne dyne force 1 dyne = 10^-5 N = 10^-5 kg*m/s^2 erg erg energy 1 erg= 10^-7 J = 10^-7 kg*m^2/s^2 lb pound force 1 lb = 4.45 N = 4.45 kg*m/s^2 ton ton force 1 ton = 2000 lb = 8900 kg*m/s^2 Pa Pascal pressure 1 Pa = 1 N/m^2 = 1 kg/m*s^2 kPa kilo-Pascal pressure 1 kPa = 1000 Pa = 10^3 kg/m*s^2 atm atmosphere pressure 1 atm = 14.7 lb/in^2 = 1.01E5 Pa = 1.01E5 kg/m*s^2 cal calorie energy 1 cal = 4.19 J = 4.19 kg*m^2/s^2 kcal kilocalorie energy 1 kcal = 1000 cal = 4190 kg*m/s^2 eV electron volt energy 1 eV = 1.60E-19 J = 1.60E-9 kg*m^2/s^2 kWh kilo-Watt hour energy 1 kWh = 3.6E6 J = 3.6E6 kg*m^2/s^2

## Multiple choice problems

Some problems require you to enter all of several possible choices that are correct, for example ACEG. In this case, enter the letters corresponding to the choices in one string without any spaces separating the letters.

## Problems requiring a symbolic functional expression for the answer

Follow the conventions explained in the WebWork section on Accepted math functions.

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