The metric system evolved into the International System of Units (SI Units) which was adopted in 1960. The key features of the SI are decimalization, prefixes for units, and base units defined by physical constants like the speed of light. The English system is still used in the US but has been replaced in most other places by the SI.

2. The metric system is the common
system of reference units used in science.
The metric system has evolved into the
International System of Units (SI Units) from
the French “ Systẻme International d’ Unités”.
It was adopted in 1960 by the 11th General
Conference on Weights and Measures.

3. • An expanded and modified version of the
metric system, the International System
addresses the needs of modern science for
additional and more accurate units of
measurement.

4. • The key features of the International System are
decimalization, a system of prefixes, and a
standard defined in terms of an invariable
physical measure. The English system, on the
other hand, is a system of measurement that
still used in the United States, but has been
replaced in most parts of the International
System.

5. LENGTH VOLUME MASS
1 in = 2.54cm 1 qt = 946 ml 1 lb = 454g
1 m = 39.37 in 1 L = 1.057 qt 1 kg = 2.2 lb
1 mi = 1.609 km 1 L =2.12 pints 1 oz = 23.35 g
1 km = 0.62137 mi 1 L = 4.23 cups 1 short ton = 2000 lbs
1 A = 10ˉ¹º m 1 tsp = 4.93 mL
1 tbsp = 14.79 mL 1 metric ton = 1000 kg
1 fl oz = 29.6 mL = 1.10 short
1 gal = 3.79 L ton

6. Base Units of International System
The International System has base units from
which all other units in the system are
derived. The standards for the base units,
except for the kilogram are defined by
unchanging and reproducible physical
occurrences. For example, the meter is
defined as the distance traveled by light in a
vacuum 299 792 458 of a second. The
standard for a kilogram is platinum- iridium
cylinder kept at the International Bureau of
Weights and Measures in Serves, France.

7. FUNDAMENTAL SI UNITS
TABLE 2-2
QUANTITY UNIT SYMBOL
Length Meter m
Mass Kilogram kg
Time Second s
Electric current Ampere A
Temperature Kelvin K
Amount of Mole mol
matter
Luminous Candela cd
intensity

8. METRIC PREFIXES AND EQUIVALENTS
TABLE 2-3
PREFIX SYMBOL MULTIPLYING FACTOR
exa- E 1 000 000 000 000 000 000 1018
peta- P 1 000 000 000 000 000 1015
tera- T 1 000 000 000 000 1012
giga- G 1 000 000 000 109
mega- M 1 000 000 106

9. PREFIX SYMBOL MULTIPLYING FACTOR
kilo- k 1 000 103
hecto- h 100 102
deca- da 10
10
deci- d 0.1 10-1
centi- c 0.01 10-2

10. PREFIX SYMBOL MULTIPLYING FACTOR
milli- m 0.001 10-3
micro- ɥ 0.000001 10-6
nano- n 0.000000001 10-9
pico- p 0.000000000001 10-12
femto- f 0.000000000000001 10-15
alto- a 0.000000000000000001 10-18

11. CHANGING UNITS OF
MEASUREMENT
The factor units method, or
dimensional analysis, provides a
systematic, straightforward way to solve
a problem. It gives a clear understanding
of the principles involved, helps in
learning to organized and evaluate data,
and helps identify errors because
unwanted units are not eliminated if the
setup of the problem is incorrect.

12. The basic steps for changing units of
measurement are the following
• Read the problem carefully to determine what is to be
solved for, then write it down.
• Tabulate the data given in the problem. Even in
tabulating data, it is important to label all factors and
measurements with the proper units.
• Determine which principles are involved and which
unit relationships are needed to solve the problem.
Sometimes it is necessary to refer to tables for needed
data.

13. * Set up the problem in a neat, organized, and
logical fashion, making sure that unwanted units
cancel. Use sample problems in the text as guides
for making setups.
* Proceed with the necessary mathematical
operations. Make certain that the answer contains
the proper number of significant figures.
* Check the answer to see if it is reasonable.

14. MASS AND WEIGHT
Mass and weight are often used inter-
changeably, but the two words have different
meanings. The mass of a body is defined as the
amount of matter in that body. The mass of an object
is a fixed and unvarying quantity that is independent
of the objects location.
The weight of a body is the measure of the
Earth’s gravitational attraction for that body.

15. DENSITY
Density is defined as the mass per unit
volume of a material. Densities of solids and
liquids are usually reported in grams per milliliter
(g/mL), or grams per cubic centimeter (g/cm³) and
those of gases in grams per liter (g/L).
When an object floats in water, it has a
density lighter than water and when it sinks, it is
heavier that water.
The density of the substance can be used
to identify the substance. Density is an important
physical property of substance.

16. DENSITIES OF SOME SUBSTANCES
TABLE 2-4
SUBSTANCE DENSITY [g/cm³]
Oxygen 0.0013
Sugar 1.6
Salt 2.2
Iron 7.9
Copper 8.9
Lead 11.3
Mercury 13.6

17. SUBSTANCE DENSITY [g/cm³]
Gold 19.3
Human fat 0.94
Cork 0.22-0.26
Earth 5.54
Water (4.0º C) 1.000
Ice (-10ºC) 0.917

18. SCIENTIFIC GRAVITY
The specific gravity of a substance is the
ratio of the density of that substance the density
of water of 4ºC.

19. TEMPERATURE MEASUREMENT
Temperature is a measure of the hotness
or coldness of matter and is usually expressed
in degrees Fahrenheit, degrees Celsius, or
Kelvin. It measures the intensity of energy of
the particles in a substance. For example, the
particles of water in a cup of hot water at 60ºC
are more energetic than particles in a glass of
cold water at 5ºC. Tempe-rature and heat are
related but they are often confused.

20. RELATIONSHIP BETWEEN
FAHRENHEIT, CELSIUS, AND
KELVIN TEMPERATURE
CONDITION FAHRENHEIT CELSIUS KELVIN
Boiling point of water 212º 100º 373
A very hot day 104º 40º 313
Normal body 98.6º 37º 310
temperature
A cool day 50º 10º 283
Freezing point of 32º 0º 273
water
Mixture of salt and ice 0º -17.8º 255.2

21. HEAT : A QUANTITATIVE
MEASUREMENT
Heat is the form of energy that is
transferred between samples of matter because
of a difference in their temperatures. A cup of hot
water at 60ºC can have the same temperature as
a bathtub of water, but the bathtub of water will
melt more than the cup of water will. More heat
can flow out of the bathtub of water than can flow
out of the cup of water at the same tempeerature.