Units
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.
Contents
Problems requiring a numerical answer[edit]
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[edit]
The numerical value may be written as a floating point decimal, for example 0.00314159
, or in scientific notation as either 3.14159E3
(as in FORTRAN) or 3.14159*10^3
(with *
signifying multiplication, and ^
signifying exponentiation; note in using the FORTRANlike 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 Available_Functions. Note that trigonometric functions assume the argument is expressed in radians and not degrees.
Units[edit]
The units may be any compound expression of the form:[unit]_{1}^n_{1}*[unit]_{2}^n_{2}*...*[unit]_{3}^n_{3}/ [unit]_{4}^n_{4}*[unit]_{5}^n_{5}*...*[unit]_{6}^n_{6}
where [unit]_{i}
is any of the unit abbreviations listed below, and the n_{i}
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

lightyear

light year  length  1 lightyear = 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

kiloHertz  frequency  1 kHz = 1000 Hz = 10^3 s^1

MHz

megaHertz  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

microNewton  force  1 microN = 10^6 N = 10^6 kg*m/s^2

uN

microNewton  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

kiloJoule  energy  1 kJ = 1000 J = 10^3 kg*m^2/s^2

lbf

footpound  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

kiloWatt  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

kiloPascal  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 = 1.60E19 J = 1.60E9 kg*m^2/s^2

kWh

kiloWatt hour  energy  1 kWh = 3.6E6 J = 3.6E6 kg*m^2/s^2

Units Available in WeBWorK[edit]
Some WeBWorK problems ask for answers with units. Below is a list of basic units and how they need to be abbreviated in WeBWorK answers. In some problems, you may need to combine units (e.g, velocity might be in ft/s
for feet per second).
Unit  Abbreviation 

Time  
Seconds  s 
Minutes  min 
Hours  hr 
Days  day 
Years  yr 
Milliseconds  ms 
Distance  
Feet  ft 
Inches  in 
Miles  mi 
Meters  m 
Centimeters  cm 
Millimeters  mm 
Kilometers  km 
Angstroms  A 
Light years  lightyear 
Mass  
Grams  g 
Kilograms  kg 
Slugs  slug 
Volume  
Liters  L 
Cubic Centimeters  cc 
Milliliters  ml 
Force  
Newtons  N 
Dynes  dyne 
Pounds  lb 
Tons  ton 
Work/Energy  
Joules  J 
kilo Joule  kJ 
ergs  erg 
foot pounds  lbf 
calories  cal 
kilo calories  kcal 
electron volts  eV 
kilo Watt hours  kWh 
Electric  
Charge Coulombs  C 
Voltage Volts  V 
milivolts  mV 
kilovolts  kV 
megavolts  MV 
Capacitance Farad  F 
milifarad  mF 
microfarad  uF 
Resistance ohms  ohm 
kiloohm  kohm 
Misc  
Amperes  amp 
Moles  mol 
Degrees Centrigrade  degC 
Degrees Fahrenheit  degF 
Degrees Kelvin  degK 
Angle degrees  deg 
Angle radians  rad 