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MEASUREMENT
Chapter One: Measurement
1.1 Measurements
1.2 Time and Distance
1.3 Converting Measurements
1.4 Working with Measurements
Section 1.1 Learning Goals
Define measurement.
Compare English and SI measurements.
Become familiar with metric prefixes.
Investigation 1A
Measurement
Key Question:
Are you able to use scientific tools to make
accurate measurements?
1.1 Measurements
A measurement is a
determination of the
amount of something.
A measurement has
two parts:
 a number value and
 a unit
1.1 Two common systems
The English System is used for everyday
measurements in the United States.
Miles, yards, feet, inches, pounds, pints,
quarts, gallons, cups, and teaspoons are all
English system units.
In 1960, the Metric System was revised and
simplified, and a new name was adopted—
International System of Units.
1.1 International System of
Measurement (SI)
The acronym SI comes from the French
name Le Système International d’Unités.
SI units form a base-10 or decimal system.
In the metric system, there are:
 10 millimeters in a centimeter,
 100 centimeters in a meter, and
 1,000 meters in a kilometer.
1.1 The meter stick
A meter stick is
1 meter long and
is divided into
millimeters and
centimeters.
1.1 The meter stick
Each centimeter is divided into ten
smaller units, called millimeters.
What is the length in cm?
Chapter One: Measurement
1.1 Measurements
1.2 Time and Distance
1.3 Converting Measurements
1.4 Working with Measurements
Section 1.2 Learning Goals
Explain the meaning of time in a
scientific sense.
Discuss how distance is measured.
Use a metric ruler to measure distance.
1.2 Time and Distance
Two ways to think
about time:
 What time is it?
 How much time?
A quantity of time is
also called a time
interval.
1.2 Time
Time comes in mixed units.
 Seconds are very short.
 For calculations, you may need to convert
hours and minutes into seconds.
How many seconds is
this time interval?
1.2 Distance
 Distance is the amount
of space between two
points.
 Distance is measured in
units of length.
 The meter is a basic SI
distance unit.
In 1791, a meter was defined as one ten-millionth of
the distance from the North Pole to the equator.
What standard is used today?
1.2 Metric prefixes
 Prefixes are added to the names of basic
SI units such as meter, liter and gram.
 Prefixes describe very small or large
measurements.
Chapter One: Measurement
1.1 Measurements
1.2 Time and Distance
1.3 Converting Measurements
1.4 Working with Measurements
Section 1.3 Learning Goals
Write conversion factors.
Apply the decimal point rule to convert
between metric quantities.
Use dimensional analysis to convert
English and SI measurements.
1.3 Converting units
To convert 1,565 pennies to the dollar
amount, you divide 1,565 by 100 (since
there are 100 pennies in a dollar).
Converting SI units is just as easy as
converting pennies to dollars.
Solving Problems
 Convert 655 mm to m
1. Looking for:
 …the distance in meters
2. Given:
 …distance = 655 millimeters
3. Relationships:
 Ex. There are 1000 millimeters in 1 meter
4. Solution:
655 mm = .655 meters
Solving Problems
Convert 142 km to m
1. Looking for:
 …the distance in meters
2. Given:
 …distance = 142 kilometers
3. Relationships:
 Ex. There are ? meters in 1 kilometer?
4. Solution:
 Use the conversion tool.
Solving Problems
Convert 754,000 cm to km
1. Looking for:
 …the distance in kilometers
2. Given:
 …distance = 754,000 centimeters
3. Relationships:
 Ex. There are ? cm in 1 m?
 There are ? m in 1 km?
4. Solution:
 Use the conversion tool.
1.3 Converting units
 A conversion factor
is a ratio that has
the value of one.
 This method of
converting units is
called dimensional
analysis.
 To do the
conversion you
multiply 4.5 feet by
a conversion factor.
Solving Problems
Convert 4.5 ft to cm
1. Looking for:
 You are asked for the distance in cm
2. Given:
 You are given the distance in ft.
3. Relationships:
 Ex. There are ? cm in 1 ft? 30.48 cm = 1 ft
4. Solution:
 Make a conversion factor from equivalent
1.3 Converting units
 Use the correct
conversion factor to
convert:
175 yds. to m.
2.50 in. to mm.
Chapter One: Measurement
1.1 Measurements
1.2 Time and Distance
1.3 Converting Measurements
1.4 Working with Measurements
Section 1.4 Learning Goals
Determine the number of significant
figures in measurements.
Distinguish accuracy, precision, and
resolution.
Compare data sets to determine if
they are significantly different.
Investigation 1B
Conversion Chains
Key Question:
How can you use unit canceling to solve
conversion problems?
1.4 Working with Measurements
 Accuracy is how close a measurement is
to the accepted, true value.
 Precision describes how close together
repeated measurements or events are to
one another.
1.4 Working with Measurements
 In the real world it is
impossible for
everyone to arrive at
the exact same true
measurement as
everyone else.
Find the length of the
object in centimeters.
How many digits does your
answer have?
1.4 Working with Measurements
Digits that are always significant:
1. Non-zero digits.
2. Zeroes between two significant digits.
3. All final zeroes to the right of a decimal
point.
Digits that are never significant:
4. Leading zeroes to the right of a decimal
point. (0.002 cm has only one significant
digit.)
5. Final zeroes in a number that does not
have a decimal point.
Solving Problems
What is area of 8.5 in. x 11.0 in. paper?
1. Looking for:
 …area of the paper
2. Given:
 … width = 8.5 in; length = 11.0 in
3. Relationship:
 Area = W x L
4. Solution:
 8.5 in x 11.0 in = 93.5 in2
# Sig. fig = 94 in2
1.4 Working with Measurements
 Using the bow
and arrow
analogy explain
how it is possible
to be precise but
inaccurate with a
stopwatch, ruler
or other tool.
1.4 Resolution
 Resolution refers to the smallest
interval that can be measured.
 You can think of resolution as the
“sharpness” of a measurement.
1.4 Significant differences
 In everyday conversation, “same” means
two numbers that are the same exactly,
like 2.56 and 2.56.
 When comparing scientific results
“same” means “not significantly
different”.
 Significant differences are differences
that are MUCH larger than the estimated
error in the results.
1.4 Error and significance
 How can you tell if two results are the
same when both contain error
(uncertainty)?
 When we estimate error in a data set, we
will assume the average is the exact
value.
 If the difference in the averages is at
least three times larger than the
average error, we say the difference is
“significant”.
1.4 Error
 How you can you
tell if two results
are the same when
both contain error.
Calculate error
Average error
Compare average
error
Solving Problems
Is there a significant difference in data?
1. Looking for:
 Significant difference between two data sets
2. Given:
 Table of data
3. Relationships:
 Estimate error, Average error, 3X average error
4. Solution:
 Math answer: 93.5 in2
 Determine # of significant figures = 94 in2
Investigation 1C
Significant Digits
Key Question:
How do we make precise measurements?
Nanotechnology
What if biological
nanomachines could seek
out a broken part of a cell
and fix it? How can a
nanomachine mimic
nature’s ability to heal?
These are the cutting-edge questions that
nanomedicine scientists are trying to
answer.