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
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 Available_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
|
Units Available in WeBWorK
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 | light-year |
| 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 |
| kilo-ohm | kohm |
| Misc | |
| Amperes | amp |
| Moles | mol |
| Degrees Centrigrade | degC |
| Degrees Fahrenheit | degF |
| Degrees Kelvin | degK |
| Angle degrees | deg |
| Angle radians | rad |
