2. Contents
Measurements & SI Units
Prefixes
Unit Conversions
The Metric System
Length, Volume, Mass, Weight etc.
3. What is measurement?
The ability to describe an observation is important.
A description is a statement that reports what has been
observed.
A measurement is a description that includes a number and
a unit.
4. What is a Unit?
The standard measure of each kind of physical quantity.
It is a definite magnitude of a quantity, defined and
adopted by convention or by law, that is used as a standard
for measurement of the same kind of quantity.
For Example: Length is a physical quantity and meter is its
unit. Mass, time, temperature are also physical quantities.
6. Base Units
The SI is founded on seven SI base units for seven base
quantities assumed to be mutually independent.
These base units are:
Meter for Length, Kilogram for Mass, Second for Time,
Ampere for Electric Current, Kelvin for Temperature,
Mole for amount of a Substance & Candela for Intensity
of Light.
8. What is the International System of Units?
The modern metric system is called the International
System of Units (SI).
The SI units are the language for all scientific
measurements.
There are seven base units used to express the different
quantities: length, mass, time, temperature, amount of
substance, electric current, and light intensity.
9. What are the SI units?
Length, mass, time, and temperature are the most
commonly used quantities.
Meter is the unit of length. Length is measured with
a meterstick, ruler, or measuring tape.
Kilogram is the unit for mass. Mass is measured with
a balance.
Second is the unit for time. Time is measured using a
stopwatch.
Kelvin is the unit for temperature. Temperature is
measured using a thermometer.
10. Prefixes
Prefix Meaning in words Meaning
Kilo Thousand 1,000
Hecto Hundreds 100
Deka Tens 10
Deci Tenths .1
Centi Hundredths .10
Milli Thousandths .100
A prefix is one or more letters or syllables added
to the beginning of a word to change its meaning
18. What to do first in the problem
4.5 m = __ cm ?
Find YOUR step, then move!!!
Basic
Deci
Centi
Milli
Deka
Hecto
Kilo
Start here at Meters and
Move DOWN to Centimeters.
Decimal place moves to the
RIGHT the same number
of steps.
*
*
4.5
Basic
Liter
Meter
Gram
19. As You Move The Decimal You Will Need
To Add Zeros.
4 . 5 0 .
21. Quiz Time
1) 28 cm = ? mm
2) 438 cm = ? m
3) 72 g = ? mg
4) 202 g = ? Kg
5) 2 L = ? mL
22. How did We do?
1. 28 cm = 280 mm
2. 438 cm =
3. 72 g =
4. 202 g =
5. 2 L =
4.38 m
72,000 mg
0.202 kg
2,400 L
23. Dimensional Analysis Rule
1. Write down the “given” unit.
2. Draw a horizontal & vertical line “picket fence”.
3. Write “required” / “given” on the fence
4. Enter proper numbers for “required units & “given”
units
5. Cancel units & do the math.
Required Unit
= Req. Unit
Given Unit
Conversion factor
Given Unit
24. For example: Convert 25 km to meters
Use the conversion factor that allows units to cancel.
1000 m or 1 km
1 km 1000 m
1000 m
= 25 × 1000
1 km
25 km
= 25000 m
picket
fence
Given
Conversion
factor
Required
25. For example: Convert 33 meter to inches.
Use the conversion factor that allows units to cancel.
3.28 ft. = 33 × 3.28 × 12
1 m
33 m
= 1298.8 inches
Given
Conversion
factor Required
1 m 1 ft.
3.28 ft. 12 inches.
&
12 inches
1 ft.
Conversion
factor
27. Length Conversions
1 centimeter = 10 millimeter 1 cm = 10 mm
1 decimeter = 10 centimeter 1 dm = 10 cm
1 meter = 100 centimeter 1 m = 100 cm
1 meter = 10 decimeter 1 m = 10 dm
1 kilometer = 1000 meters 1 km = 1000 m
Metric Unit Conversions
Weight Conversions
1 gram = 1000 milligrams 1 g = 1000 mg
1 decagram = 10 gram 1 dag = 10 g
1 kilogram = 1000 grams 1 kg = 1000 g
1 ton = 1000 kilograms 1 t = 1000 kg
28. Length Conversions
1 inch = 2.54 cm 1 foot = 30.48 cm
1 yard = 91.44 centimeter 3.28 foot = 1 m
1 mile = 1609.344 m 1 mile = 1.609 km
Imperial to Metric Unit Conversions
Volume Conversions
1 pound = 453.59 grams 1 lb. = 453.59 g
1 ounce = 28.35 grams 1 oz. = 28.35 g
1 gallon = 3.79 liters 1 gal. = 3.79 L
1 ton = 1000 kilograms 1 t = 1000 kg
29. Quiz Conversions
1 km/hr. m/s = 0.2777 m/s
1 inch m = 0.0254 m
1 cm m = 0.01 m
1 g kg = 0.001 kg
1 L mL = 1000 mL
1 Mile m = 1609.34 m
1 °C °F = 33.8 °F
30. Practice (Assignment)
How many cm. are there in 5.54 inches?
18.2 km to m?
60 Miles/hr. to m/hr.?
550 kg to mg?
1298 g to pound?
88 Miles/hr. to m/sec.?
31. The Metric System
---The Universal Language of Measurement---
Metric System – scientists & engineers use this language
to communicate
The metric system is often referred to as the
International System of Units (abbreviated “SI”)
The metric system is based on the number 10 and
multiples of 10.
33. Length
The distance between two points
Unit Description
Meter
The basic unit of length in the metric system
1 meter = 1 m
Centimeter
One Hundredth of a meter
1 cm = 1/100 m = 0.01 m
100 cm = 1 m
Millimeter
One Thousandth of a meter
1 mm = 1/1000 m
1000 mm = 1m
Kilometer
One Thousand Meters
1 km = 1000m
1 m = 1/1000 km
Light year
The distance light travels in one year
Speed of light = 300,000 km/s
34. Volume
The amount of space an object takes up
1cm
1cm
V = 1 cm3 = 1 mL
1cm
Unit Description
Liter The basic unit of volume in the metric system
1 Liter = 1 L
Milliliter One Thousandth of a Liter
1 mL = 1/1000 L = 0.001 L
Millimeter Milliliters and Liters are used to measure the volume of
Liquids
Cubic centimeters The Metric unit used to measure the volume of
Solids
35. Mass
A measure of the amount of matter in an object
Unit Description
Kilogram The Basic Unit Of Mass In The Metric System
1 kg = 1000 grams
Gram One Thousandth Of A Kilogram
1 g = 1/1000 kg = 0.001 kg
1000 g = 1 kg
Milligram One Thousandth Of A Gram
1 mg = 1/1000 g = 0.001 g
1000 mg = 1 g
36. Weight
a measure of the attraction between two objects due to gravity
• Gravity - a force of attraction between two masses.
• The strength of the gravitational force between two
objects depends on the masses of the objects and the
distance between them:
a) The greater the mass, the greater the gravitational force.
b) The greater the distance between the two objects, the weaker
the gravitational force between them
• Newton (N) - the basic unit of weight in the metric
system.
37. Mass vs. Weight
• An object has a universal mass, but may have different
weight depending on gravity.
• The mass of an object does not change.
• The weight of an object changes as a result of changes
in gravity.
• A pineapple on earth weighs more than on the moon
because the earth’s gravity is greater. But the
pineapple’s mass always remains the same wherever
you go (unless you get hungry and eat it!).
38. Density
a measure of the amount of matter that occupies a unit certain volume
• Density = mass/volume
(units are usually g/mL)
The density of water = 1.00 g/mL
This means that one gram of water occupies one milliliter of
volume.
The density of oil = 0.91 g/mL
If lighter fluids float on heavier fluids, do you expect water to
float on oil?
39. Sand grains
If the human body is nearly 70% water, is it
possible to float in quicksand? Should you get
worried?
40. Temperature
A measure of how hot or cold something is
• Celsius = a unit of temperature in the metric system
• Water freezes at 0° C.
• Water boils at 100° C.
• Normal body temperature is 37° C
• Room temperature is 20° C.
41. • Kelvin = another unit of temperature in the metric system.
• The lowest possible temperature is “0” Kelvin (-273 ° C).
This is Absolute Zero.
Temperature
A measure of how hot or cold something is
Temperature Conversion Formulas
From To Formula
Celsius Fahrenheit F= (°C × 9/5) + 32
Celsius Kelvin K= (°C + 273.16)
Fahrenheit Rankin R= (°F + 459.69)
