Measurements in Science
Using the Metric System
Who Uses Metric?
• Most of the world uses the metric system.
• The only countries not on this system are the
United States, Myanmar, and Liberia.
• The metric system is based on 10s.
History of the Metric System
• The metric system was first proposed in 1791.
• It was adopted by the French revolutionary
assembly in 1795, and the first metric standards
(a standard meter bar and kilogram bar) were
adopted in 1799.
• There was considerable resistance to the system
at first, and its use was not made compulsory in
France until 1837.
• The first countries to actually require use of the
metric system were Belgium, the Netherlands,
and Luxembourg, in 1820.
Metric Units Smaller than 1
• Units smaller than a meter have Latin prefixes:
• Deci - means 1/10
• 10 decimeters make a meter.
• Centi - means 1/100
• 100 centimeters make a meter.
• Milli - means 1/1,000
• 1,000 millimeters make a meter.
Metric Units Greater than 1
• Units larger than a meter have Greek prefixes:
• Deka - means 10
• a dekameter is 10 meters.
• Hecto - means 100
• a hectometer is 100 meters.
• Kilo - means 1,000
• a kilometer is 1,000 meters.
What Do We Measure in Metric Units?
• Mass - the amount of matter in an object.
• Length - the distance between two fixed
points.
• Volume - the amount of space an object takes
up.
• Temperature - the measure of hotness or
coldness.
• Density - mass per unit volume of a
substance.
Mass
• The amount of matter in an object.
• Mass is different than weight.
• Measured with a triple beam balance or scale.
Mass
• The standard unit for Mass in the metric
system is grams.
• We abbreviate these masses as follows:
1 milligram = 1 mg
1 centigram = 1 cg
1 decigram = 1 dg
1 gram = 1 g
1 kilogram = 1 kg
• For reference
– 1 g is about the mass of a paper clip
– 1 kg is about the mass of a liter of water.
Length
• The distance between two fixed points.
Length
• The standard unit of length in the metric system
is the meter.
1 Millimeter (mm) = 0.001 Meter
1 Centimeter (cm) = 0.01 Meter
1 Decimeter (dm) = 0.1 Meter
1 Kilometer (km) = 1000 Meters
• For Reference
–
–
–
–
1 m is a little longer than 1 yard or 3 ft.
1 m is about half the height of a very tall adult.
1 cm is nearly the diameter of a dime, a little less than half an inch.
1 mm is about the thickness of a dime.
Volume
• The amount of space an object takes up.
Volume
• The standard unit of volume in the metric
system is the liter.
1 Milliliter = 1 ml
1 Centiliter = 1 cl
1 Deciliter = 1 dl
1 Liter = 1 L
1 Kiloliter = 1 kl
• For reference
– 1 ml equals 1 Cubic Centimeter in volume.
Temperature
• How hot or cold
something is.
Temperature
• The standard unit of temperature
in the metric system is the Celsius.
• For reference
– The boiling point of water (at sea level) is
100°Celsius, or 100°C.
– The freezing point of water (at sea level) is 0° Celsius.
– A hot day is about 30° Celsius.
Temperature Conversions
•
O C=
( OF - 32 ) / 1.8
•
O F=
( O C x 1.8 ) + 32
•
O K=
C + 273.0
– Examples
• 0 O C = 32 O F
• 37 O C = 98.6 O F
Density
• Mass Per Unit Volume of a Substance.
• D= m (g)
v (cm3)
• m = mass
• unit = gram
• v = volume
• unit = cubic meters (cm3)
Converting from one unit to another
• 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
• Page R-5 in the back of your agenda has many
measurements and conversions for reference.
Conversion Problems
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
1 km = _____ m
1 cm = _____ mm
1 cm = _____ m
5 g = _____ mg
0.3 ml = _____ l
2 l = _____ ml
1.024 km = _____ m
640.128 ml = _____ l
1 cc = _____ ml
1500 cc = _____ l
Conversion Problems Answers
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
1000
10
0.01
5000
0.0003
2000
1024
0.640128
1
1.5