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CHAPTER ONE: MEASUREMENT
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?
Learn to think SI
1 cm is about the width of your little finger
1mL is about the same volume as 10 drops
of water
1g is about the mass of one large paperclip
21degrees Celsius is a comfortable room
temperature.
Questions pg. 8
Answer question numbers
2,6,7,8,9, 10
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?
REACTION TIME
CHALLENGE PG. 9
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.
 English vs Customary
 Study Jams
Remember king henry: K, H, D,( m, L,G), d, c, m
 A meter stick is a good tool to use for measuring
ordinary lengths in the lab.
 A meter stick is 1 meter long and is divided into
millimeters and centimeters.
Questions pg. 12
Answer questions numbers 2,4,5,7,8
1.3 Converting units
 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
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.
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.
Metric Practice
Brain pop
More Metric Practice
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.
Accuracy and Precision
 Using the bow
and arrow
analogy explain
how it is possible
to be precise but
inaccurate with a
stopwatch, ruler
or other tool.
Resolution
 Resolution refers to the smallest
interval that can be measured.
 You can think of resolution as the
“sharpness” of a measurement.
brain pop
Balloon toss activity
 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?
Significant Digits
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.
** A decimal point is used after a whole number ending in zero to
indicate that a final zero is significant. Thus 50. cm has two
significant digits not one **
Practice
How many significant digits does each
of the following numbers have?
40 cm, 4cm, 4.0 cm, 40.cm, 45 cm, 450 cm
450.cm
 Convert 1.10 miles to km and report your
answer with 2 significant digits. Use the
relationship 1mi= 1.6 km
Answers
40cm=1
4cm=1
4.0cm=2
40.cm=2
45cm=2
450cm=2
450.=3
1.10x1.6=1.76= 1.8km
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
Significant Digits Pracitice
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.
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”.
Error
 How you can you tell if
two results are the
same when both
contain error.
 The estimated error
is calculated by
taking the group
average time and
subtracting each
individual trial time.
 The estimated error
is an absolute value;
drop any negative
signs
Is there a significant difference in data?
1.
Looking for:
 Significant difference between two data sets
2.
Given:
1.
Trial
Group 1
mass (g)
Est. Error
Group 2
mass (g)
Est. Error
1
2.6
0.1
2.1
0.0
2
2.7
0.0
2.2
0.1
3
2.8
0.1
2.1
0.0
Average
2.7
0.1
2.1
0.03
Relationships: Estimate error, Average error, 3X average
error
3.
Solution:
 The difference between the averages2.7-2.1=.6
 The difference of 0.6 is six times greater that the largest
estimated error(0.1) so the results are significantly
different.
Sig Diff in Meas Skill Sheet.pdf
Answer Questions pg. 23
Numbers 1,3,4,5