Transcript Standards of Measurement

Standards of Measurement
Chapter 1 Section 2
Units and Standards
Standard-an
exact quantity that
is agreed upon to use for
comparison
 hands
 feet
 piece
of string
Measurement Systems
English
 inch
 pound
 ounce
Metric
 centimeter
 gram
 liter
Fundamental Units
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There are 7 fundamental units. All other units are
a combination of these units.
kilogram
meter
second
kelvin
candela
mole
ampere
Derived Units
A
unit that is a combination of
fundamental units
 Newton-measurement of force
combination of kg, m, and s-kg.m/s2
 Joule-measurement of energy
combination of kg, m, and s-kg.m2/s2
International System of Units
– 1960 renamed the metric
system to SI to indicate an
improved version
 standard system of measurement
used worldwide
 prefixes based on powers of 10
 SI
SI Prefixes

Kilo-k-1000
 Centi-c-0.01
 Milli-m-0.001
 Convert 23 km to mm
 Convert 75 g to kg
Measuring Distance
Length (distance)
l (d)
distance between points
units of meter, centimeter, or
kilometer
Appropriate use of units
Meter, m
1st
defined at 1/10,000,000 the
distance from north pole to
equator pass through Lyons,
France
1983 light traveling in a
vacuum for 1/299,792,458 s
Measuring Matter
Mass
 amount
of matter in an object
 units are kilogram
Kilogram, kg
Mass
of small platinum-iridium
metal cylinder
Not reproducible with natural
occurrence
Measuring Time
Time
interval
between two events
unit is second
Second, s
 First
defined as 1/86,400 of a solar day
 Universe is expanding and Earth’s
rotation is slowing down so time was
not constant
 1960’s atomic clocks developed
 Now so many vibrations of Cs-133
atom
Measuring Temperature
 Temperature
 the
measure of the hotness or
coldness
 units are Celsius or Kelvin
Kelvin, K
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Originally Cesius based on the boiling and
freezing points of water
 Now based on the triple point of water.
 Triple point is when all three phases of
water are present