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20 APPENDIX: PHYSICAL UNITS
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might be in terms of “m/sˆ2” or meters per second squared. This could also be expressed
as“m/s/s”. Units of Newton-meters (for torque) would be entered as “N*m”. Parentheses
may be used to guarantee the correct sense of the unit. Kilometers per Ampere-hour could
be written as “km/(A*hr)” or “km/A/hr” but not “km/A*hr”. The last option would be
interpreted as kilometer times hours per Ampere.
LON-CAPA will automatically perform some conversions between units of the same di-
mension when units are provided for a problem. You can provide an answer of “1.45 km”
for a distance. If the computer expects the answer in cm, it will convert your answer before
comparing against the numerical solution.
Please note that if your units are inappropriate, the computer has no way of checking
the appropriateness of your answer. If units are required, only once appropriate units are
provided will the system check your numerical answer.
Base Units
# name
symbol
comment
meter
m
# length
kilogram
kg
# mass
second
s
# time
ampere
A
# electric current
kelvin
K
# thermodynamic temperature
mole
mol
# amount of substance
candela
cd
# luminous intensity
decibel
dB
# log of pressure amplitude
Prefixes
#
Prefix
symbol
factor
yotta
Y
10^{24}
zetta
Z
10^{21}
exa
E
10^{18}
peta
P
10^{15}
tera
T
10^{12}
giga
G
10^9
mega
M
10^6
kilo
k
10^3
hecto
h
10^2
deca
D
10^1
deci
d
10^-1
centi
c
10^-2
milli
m
10^-3
micro
u
10^-6