Units of Measure
Measuring Devices:
Graduated
Cylinder
The Metric System
Length:
- 1000 millimeters = 1 meter
- 100 centimeters = 1 meter
- 1000 meters = 1 kilometer
Mass (or weight):
- 1000 milligrams = 1 gram
- 1000 grams = 1 kilogram
- 1000 kilograms = 1 metric ton
Volume:
- 1000 milliliters = l liter
- 1000 liters = 1 cubic meter
Area:
- 10 000 square meters = 1 hectare
- 100 hectares = 1 square kilometer
Prefixes:
- micro means 1/1 000 000
- milli- means 1/1000
- centi- means 1/100
- kilo- means 1000
- mega- means 1 000 000
Symbols:
- m for meter
- mm for millimeter
- cm for centimeter
- km for kilometer
- g for gram
- mg for milligram
- kg for kilogram
- L for liter
- mL for milliliter
- m2 for square meter
- m3 for cubic meter
- km2 for square kilometer
- t for metric ton
- ha for hectare
Some special relationships:
- 1 milliliter = 1 cubic centimeter
- 1 milliliter of water has a mass of approximately 1 gram
- 1 liter of water has a mass of approximately 1 kilogram
- 1 cubic meter of water has a mass of approximately 1 metric ton
Legal/official (exact) definitions of inch-pound units as set
by U.S. law:
- 1 inch = 25.4 millimeters
- 1 pound = 453.592 37 grams
- 1 gallon = 3.785 411 784 liters
Note: In Canada the inch and the pound are defined identically,
but 1 Canadian gallon = 4.546 09 liters.
Approximate conversion factors between inch-pound units and the
International System of Units (SI):
- Multiply inches by 2.54 to get centimeters (this conversion factor
is exact)
- Multiply feet by 0.305 to get meters
- Multiply miles by 1.6 to get kilometers
- Divide pounds by 2.2 to get kilograms
- Multiply ounces by 28 to get grams
- Multiply fluid ounces by 30 to get milliliters
- Multiply gallons by 3.8 to get liters
|
One of the principal advantages of the Metric System is its
use of only one unit (standard of size) for each parameter (thing that is being
measured). The metric units are interrelated in such a way that only five
fundamental standards are necessary. These fundamental standards are identified
with an * in the tables below.
MECHANICS
| Parameter: |
Metric Unit |
English Units |
time
duration, delay |
second *
s |
second, minute
hour, day |
| frequency |
hertz
1/s |
cycle per second |
length
distance, displacement |
meter
1/299 792 458 light sec
m |
inch, foot, yard
rod, chain, furlong, mile |
velocity, speed
rate of change of position |
meter per second
m/s |
foot per second
mile per hour, knot |
acceleration
rate of change of velocity |
meter per second squared
m/s2 |
foot per second squared |
mass
quantity of material |
gram *
g |
ounce, pound, ton |
force
push, pull, or weight |
newton
kg m/s2 |
pound-force |
impulse
force times time |
newton second
kg m/s |
pound-force second |
momentum
mass times velocity |
kilogram meter per second
kg m/s |
pound foot per second |
work, energy
force times distance |
joule (pronounced "jewel")
= one newton meter
kg m2/s2 |
foot pound-force |
power
rate of doing work |
watt
= one joule per second
kg m2/s3 |
foot pound-force per second
horsepower |
area
size of a surface |
square meter
m2 |
square foot, square yard
acre, square mile |
pressure
force per unit area |
pascal
newton per square meter
kg/m s2 |
pound-force per square inch |
| volume, capacity |
cubic meter (stere)
m3 |
pint, quart, gallon
cubic foot, cubic yard |
| density, heaviness |
grams per cubic centimeter
g/cm3 |
pounds per cubic foot |
HEAT
| Parameter: |
Metric Heat Unit |
English Heat Unit |
| heat energy |
joule, calorie, Calorie
1 cal = 4.186 joules
1 Cal = 4186 joules |
British Thermal Unit |
| temperature change |
kelvin * |
Fahrenheit degree |
| temperature |
degrees kelvin |
degrees Fahrenheit |
LIGHT
| Parameter: |
Metric Light Unit |
| luminous intensity |
candle * |
| luminous flux |
lumen
one candle produces 4 pi lumens |
| illumination |
lux
lumen per square meter |
| focus |
diopter
reciprocal meters |
| astronomical distance |
parsec |
ELECTRICITY & MAGNETISM (There are no English electrical
units)
| Parameter: |
Metric Electrical Unit |
| electric charge |
coulomb *
96,500 coul = 1 faraday
faraday = 1 mole of electrons |
| electromotive force (EMF) |
volt (joule per coulomb) |
| capacitance |
farad (coulomb per volt) |
| electric current |
ampere (coulomb per second) |
| electric energy |
joule (watt second)
(newton meter)
KWH = 3,600,000 joules |
| electric power |
watt (joule per second) |
| electrical resistance |
ohm
(volt per ampere) |
| electrical conductivity |
siemens (coulomb per joule)
(ampere per volt) |
| electrical field strength |
volts per meter |
| electromagnetic inductance |
henry (pl. henrys) |
| magnetic field intensity |
oersted (formerly the gauss) |
| magnetic flux |
weber (108 maxwells) |
| magnetic flux density |
tesla
weber per square meter |
| magnetomotive force |
gilbert |
|