1. Chapter 2 Physical Science Review “Physical Science Methods”
Mrs. Nell

2. Standards of Measurement
In order for a measurement to be useful, a measurement standard must be used. A standard is an exact quantity that people agree to use for comparison.
Charlemagne
Early measurements were based upon parts of the human body. A foot was the length of King Charlemagne's foot. An inch was the distance between knuckles on King Edgar's index finger. A yard was the distance between King Henry the First's nose and thumb.

3. Measurement Systems
The United States still uses the English System of Measurement primarily. Most other nations use a system of measurement based on multiples of ten.

4. The English System
Teaspoons and tablespoons
inches

5. The Metric System
The metric system, which was developed in the late 1700s, was the first system of measurement based on multiples of ten.
kilo-
hecto-
deka-
UNITS
Deci-
Centi-
Milli- km hm
dam
meters dm cm mm kg hg
dag
grams dg cg mg kL hL
daL
Liters dL cL mL

6. International System of Units
In 1960, an improved version of the metric system was introduced. The International System of Units (abbreviated SI ) is the standard system of measurement used worldwide.
Prefix
Symbol
Multiplying Factor
kilo- k
1000
deci- d
0.1
centi- c
0.01
milli- m
0.001
micro-
nano- n

7. Using SI Units
There are seven base units for measurement in SI. All other SI units can be derived from these seven base units.
Quantity Measured
Unit
Symbol
Length
Meter m
Mass
Kilogram kg
Time
Second s
Electric current
Ampere A
Temperature
Kelvin K
Amount of substance
Mole
mol
Intensity of light
Candela cd

8. Length
The SI base unit of length is the meter (m). The distance from the floor to the door knob is about 1 m.
There are 100 centimeters in a meter.
A paperclip is about 1 cm wide.
There are 10 decimeters in a meter.
A crayon is about 1 dm long.
A kilometer equals 1000 meters. The length of six city blocks is about 1 km long.
There are 1000 millimeters in a meter. The edge of a dime is about 1 mm.

9. Volume
Volume is the amount of space occupied by an object. Volume is measured in cubic units (ex- cm3).
V = L x W x H
1 dm3 = 1 liter
1 dm3 = 1000 cm3
1 mL = 1 cm3
*Measurements found by combining other SI units (like volume… which combines SI units of length) are called derived units.

10. Mass Mass is a measurement of the matter in an object.
The SI unit of mass is the kilogram (kg).
Grams (g) or milligrams (mg) may be used for measuring objects of small mass.
1 kg = 2.2 lbs
One paperclip is about 1 g
A nickel is about 5 g

11. Density
Density is the mass per unit volume of a material. Density is a derived unit. To find the density of an object you must divide its mass by its volume.

12. Density of Some Materials
The density of water is important because engineers and scientists use it when they want to know if a material will float or sink. This is known as buoyancy.
The rule is if the piece of material weighs less than the same volume of water it will float. If it weighs more it will sink.
Material
Density in kg/m3
Gold
19,300
Lead
11,300
Silver
10,500
Steel
7,850
Aluminum
2,800
Glass
2,700
Concrete
2,400
Brick
1,400
Rubber
1,100
*Water
1,000
Plastic
910
Paper
780
Pine
450
Balsa Wood
160

13. Time
Time is the interval between two events. The SI unit for time is the second (s).

14. *No degree symbol is written when using the Kelvin scale.
Temperature
The Temperature of a material is measured with a thermometer. For most scientific work, temperature is measured with the Celsius scale. On the Celsius scale water freezes at 0 degrees and boils at 100 degrees.
The SI unit of temperature is the kelvin (K). Zero on the Kelvin scale (0 K) is the coldest possible temperature (absolute zero). The Kelvin temperature can be found by adding 273 to the Celsius reading.
*No degree symbol is written when using the Kelvin scale.

15. Do you know SI???
Now go study!!!