```Honors Physical Science 2011
Mrs. Artie Orgeron
How old are you? How
tall are you? The
questions are
measurements.
Measurements are
important in both
science and everyday
life. It would be difficult
to imagine doing
science without any
measurements.
Using Scientific Notation
Why
is scientific
scientific
notation
useful?
Why is
notation
useful?
Using Scientific Notation
Why is scientific notation useful?
Scientists often work
with very large or very
small numbers.
Astronomers estimate
there are
200,000,000,000 stars
in our galaxy.
Using Scientific Notation
Scientific notation is a way of expressing a
value as the product of a number between
1 and 10 and a power of 10.
For example, the speed of light is about
300,000,000 meters per second. In
scientific notation, that speed is 3.0 × 108
m/s. The exponent, 8, tells you that the
decimal point is really 8 places to the
right of the 3.
Using Scientific Notation
For numbers less than 1 that are written
in scientific notation, the exponent is
negative.
For example, an average snail’s pace is
0.00086 meters per second. In scientific
notation, that speed is 8.6 × 10-4 m/s.
The negative exponent tells you how
many decimals places there are to the left
of the 8.6.
SI Units of Measurement
What
What units
units do
do scientists
scientists use
use for
for their
their
measurements?
measurements?
SI Units of Measurement
Scientists use
use aa set
set of
of measuring
measuring units
units
Scientists
called SI,
SI, or
or the
the International
International System
System of
of
called
Units.
Units.
SI is
is an
an abbreviation
abbreviation for
for Système
Système
••SI
International d’Unités.
d’Unités.
International
SI is
is aa revised
revised version
version of
of the
the metric
metric system,
system,
••SI
originally developed
developed in
in France
France in
in 1791.
1791.
originally
Scientists around
around the
the world
world use
use the
the same
same
••Scientists
system of
of measurements
measurements so
so that
that they
they can
can
system
interpret one
one another’s
another’s
measurements.
measurements.
SI Units of Measurement
If you told one of your
finished an assignment “in
five,” it could mean five
minutes or five hours.
Always express
measurements in numbers
and units so that their
meaning is clear.
These students’
temperature measurement
will include a number and
the unit, °C.
SI Units of Measurement
Base Units and Derived Units
SI is built upon seven metric units, known
as base units.
• In SI, the base unit for length, or the
straight-line distance between two points, is
the meter (m).
• The base unit for mass, or the quantity of
matter in an object or sample, is the
kilogram (kg).
SI Units of Measurement
Seven metric base units make up the
foundation of SI.
SI Units of Measurement
of base units.
• Volume is the amount of space taken
up by an object.
• Density is the ratio of an object’s mass
to its volume:
SI Units of Measurement
Specific combinations of SI base units
yield derived units.
SI Units of Measurement
To derive the SI unit for density,
you can divide the base unit for
mass by the derived unit for
volume. Dividing kilograms by
cubic meters yields the SI unit
for density, kilograms per cubic
meter (kg/m3).
A bar of gold has more mass
per unit volume than a feather,
so gold has a greater density
than a feather.
SI Units of Measurement
Metric Prefixes
The metric unit is not always a convenient one
to use. A metric prefix indicates how many
times a unit should be multiplied or divided by
10.
SI Units of Measurement
For example, the time it takes for a
computer hard drive to read or
write data is in the range of
thousandths of a second, such as
0.009 second. Using the prefix
milli- (m), you can write 0.009
second as 9 milliseconds, or 9 ms.
SI Units of Measurement
Metric prefixes can also make a unit larger. For
example, a distance of 12,000 meters can also
be written as 12 kilometers.
Metric prefixes turn up in nonmetric units as
well. If you work with computers, you probably
know that a gigabyte of data refers to
1,000,000,000 bytes. A megapixel is 1,000,000
pixels.
SI Units of Measurement
A conversion factor is a ratio of equivalent
measurements used to convert a quantity
expressed in one unit to another unit.
To convert the height of Mount Everest, 8848
meters, into kilometers, multiply by the
conversion factor on the left.
SI Units of Measurement
To convert 8.848 kilometers back into meters,
multiply by the conversion factor on the right.
Since you are converting from kilometers to
meters, the number should get larger.
In this case, the kilometer units cancel, leaving
you with meters.
Limits of Measurement
How
How does
does the
the precision
precision of
of
measurements
measurements affect
affect the
the precision
precision of
of
scientific
scientific calculations?
calculations?
Limits of Measurement
Precision
Precision is a gauge of how exact a
measurement is.
Significant figures are all the digits
that are known in a measurement,
plus the last digit that is estimated.
Limits of Measurement
The
The precision
precision of
of aa calculated
is
limited
limited by
by the
the least
least precise
precise
measurement
measurement used
used in
in the
the calculation.
calculation.
Limits of Measurement
A more precise time can be read from the digital clock
than can be read from the analog clock. The digital
clock is precise to the nearest second, while the analog
clock is precise to the nearest minute.
Limits of Measurement
If the least precise measurement in a
calculation has three significant
figures, then the calculated answer can
have at most three significant figures.
• Mass = 34.73 grams
• Volume = 4.42 cubic centimeters.
•
Rounding to three significant figures,
the density is 7.86 grams per cubic
centimeter.
Limits of Measurement
Accuracy
Another important quality in a
measurement is its accuracy. Accuracy
is the closeness of a measurement to
the actual value of what is being
measured.
For example, suppose a digital clock is
running 15 minutes slow. Although the
clock would remain precise to the
nearest second, the time displayed
would not be accurate.
Measuring Temperature
thermometer is
is an
an instrument
instrument that
that
AA thermometer
measures temperature,
temperature, or
or how
how hot
hot an
an
measures
object is.
is.
object
Measuring Temperature
Scale The scale indicates
temperature scale
Fahrenheit scale
Capillary tube
Colored liquid The liquid
moves up and down the
capillary tube as the
temperature changes.
Bulb The bulb
contains the
reservoir of
liquid.
the
temperature according to
how
far up or down the capillary
tube the liquid has moved.
Measuring Temperature
Compressed
scale
Liquid rises
less in a
wide tube
for the same
temperature
change.
Liquid rises
more in a
narrow tube
for the same
temperature
change.
Expanded,
Measuring Temperature
The two temperature scales that you are
probably most familiar with are the Fahrenheit
scale and the Celsius scale.
• A degree Celsius is almost twice as large as a degree
Fahrenheit.
• You can convert from one scale to the other by using
one of the following formulas.
Measuring Temperature
The SI base unit for temperature is the
kelvin (K).
• A temperature of 0 K, or 0 kelvin, refers to
the lowest possible temperature that can
be reached.
• In degrees Celsius, this temperature is
–273.15°C. To convert between kelvins
and degrees Celsius, use the formula:
Measuring Temperature
Temperatures can be expressed in degrees
Fahrenheit, degrees Celsius, or kelvins.
Assessment Questions
1.
A shopping mall has a length of 200 meters
and a width of 75 meters. What is the area of
the mall, in scientific notation?
a.
b.
c.
d.
1 × 103 m2
1.5 × 103 m2
1.5 × 104 m2
1.75 × 104 m2
Assessment Questions
1.
A shopping mall has a length of 200 meters
and a width of 75 meters. What is the area of
the mall, in scientific notation?
a.
b.
c.
d.
1 × 103 m2
1.5 × 103 m2
1.5 × 104 m2
1.75 × 104 m2
ANS: C
Assessment Questions
2.
A student measures the volume and mass of
a liquid. The volume is 50.0 mL and the mass
is 78.43 g. What is the correct calculated
value of the liquid’s density? (A calculator
a.
b.
c.
d.
1.6 g/cm3
1.57 g/cm3
1.569 g/cm3
1.5686 g/cm3
Assessment Questions
2.
A student measures the volume and mass of
a liquid. The volume is 50.0 mL and the mass
is 78.43 g. What is the correct calculated
value of the liquid’s density? (A calculator
a.
b.
c.
d.
1.6 g/cm3
1.57 g/cm3
1.569 g/cm3
1.5686 g/cm3
ANS: B
Assessment Questions
3.
How can you convert a temperature
expressed in kelvin (K) to degree Celsius (°C)?
a.
b.
c.
d.
subtract 32
subtract 273
Assessment Questions
3.
How can you convert a temperature
expressed in kelvin (K) to degree Celsius (°C)?
a.
b.
c.
d.
subtract 32
subtract 273
ANS: C
Assessment Questions
1.
The SI base unit for length is the mile.
True
False
Assessment Questions
1.
The SI base unit for length is the mile.
True
False
ANS:
F, meter
In order for news to be
useful, it must be
reported in a clear,
organized manner. Like
the news, scientific data
become meaningful only
when they are organized
and communicated.
Communication includes
visual presentations,
such as this graph.
Organizing Data
How
How do
do scientists
scientists organize
organize data?
data?
Organizing Data
Scientists can organize their data by using
data tables and graphs.
Organizing Data
Data Tables
The simplest way to organize data is to present
them in a table. This table relates two
variables—a manipulated variable (location) and
a responding variable (average annual
precipitation).
Organizing Data
Line Graphs
A line graph is useful for showing
changes that occur in related variables.
• In a line graph, the manipulated variable is
generally plotted on the horizontal axis, or xaxis.
• The responding variable is plotted on the
vertical axis, or y-axis, of the graph.
Organizing Data
Sometimes the data points in a graph
yield a straight line.
• The steepness, or slope, of this line is the
ratio of a vertical change to the
corresponding horizontal change.
• The formula for the slope of the line is
Organizing Data
Plotting the mass of water against
the volume of water yields a
straight line.
Organizing Data
A direct proportion is a relationship in which
the ratio of two variables is constant. The
relationship between the mass and the volume
of water is an example of a direct proportion.
• A 3-cubic-centimeter sample of water has a mass of 3
grams.
• A 6-cubic-centimeter sample of water has a mass of 6
grams.
• A 9-cubic-centimeter sample of water has a mass of 9
grams.
Organizing Data
This graph shows how the flow rate
of a water faucet affects the time
required to fill a 1-gallon pot.
Organizing Data
An inverse proportion is a relationship in
which the product of two variables is a
constant.
• A flow rate of 0.5 gallon per minute will fill the pot in 2
minutes.
• A flow rate of 1 gallon per minute will fill the pot in 1
minute.
• A flow rate of 2 gallons per minute will fill the pot in 0.5
minute.
Organizing Data
Faster Than Speeding Data
A modem is a device used to send and
image to a Web site, the modem in your
computer converts the data of the image into
a different format. The converted data are
then sent through a telephone line or cable
TV line. The smallest unit of data that can be
read by a computer is a binary digit, or “bit.”
A bit is either a 0 or a 1. Computers process
bits in larger units called bytes. A byte is a
group of eight bits.
Organizing Data
The table shows the data transfer rates for
modems used in home computers. Data
transfer rates are often measured in kilobits
per second, or kbps. The time required to
upload a 1-megabyte (MB) file is given for
each rate listed.
Organizing Data
Using Graphs Use the data
in the table to create a line
graph. Describe the
relationship between data
1.
Organizing Data
2. Inferring How would doubling the
data transfer rate affect the upload
time?
rate would halve the upload time.
Organizing Data
Bar Graphs
A bar graph is often used to compare a
set of measurements, amounts, or
changes.
Organizing Data
Circle Graphs
If you think of a pie cut into pieces, you have a
mental model of a circle graph. A circle graph
shows how a part or share of something relates
to the whole.
Communicating Data
How can
can scientists
scientists communicate
communicate
How
experimental data?
data?
experimental
Communicating Data
Scientists
Scientists can
can communicate
communicate results
results by
by
writing
writing in
in scientific
scientific journals
journals or
or speaking
speaking
at
at conferences.
conferences.
Communicating Data
Scientists also exchange information
through conversations, e-mails, and Web
sites. Young scientists often present their
research at science fairs.
Communicating Data
Peer review is a process in which
scientists examine other scientists’
work.
suggestions, questions, and criticism
from other scientists.
• Based on their peers’ responses, the
scientists who submitted their work for
review can then reevaluate how to best
interpret their data.
Assessment Questions
1.
Which type of graph is most useful for
showing how part of something relates to the
whole?
a.
b.
c.
d.
bar
circle
column
line
Assessment Questions
1.
Which type of graph is most useful for
showing how part of something relates to the
whole?
a.
b.
c.
d.
bar
circle
column
line
ANS: B
Assessment Questions
2.
How does a line graph generally show the
relationship between the manipulated variable and
the responding variable?
a. The manipulated variable is plotted on the x-axis, and the
responding variable is plotted on the y-axis.
b. The responding variable is plotted on the x-axis, and the
manipulated variable is plotted on the y-axis.
c. The manipulated variable is plotted on the graph, and the
responding variable is shown by the slope.
d. The responding variable is plotted on the graph, and the
manipulated variable is shown by the slope.
Assessment Questions
2.
How does a line graph generally show the
relationship between the manipulated variable and
the responding variable?
a. The manipulated variable is plotted on the x-axis, and the
responding variable is plotted on the y-axis.
b. The responding variable is plotted on the x-axis, and the
manipulated variable is plotted on the y-axis.
c. The manipulated variable is plotted on the graph, and the
responding variable is shown by the slope.
d. The responding variable is plotted on the graph, and the
manipulated variable is shown by the slope.
ANS:
A
Assessment Questions
3.
How do scientists communicate the results of
scientific investigations?
a. by writing in scientific journals or speaking at
conferences
b. using secret code
c. only through e-mail
d. by writing in literary journals
Assessment Questions
3.
How do scientists communicate the results of
scientific investigations?
a. by writing in scientific journals or speaking at
conferences
b. using secret code
c. only through e-mail
d. by writing in literary journals
ANS: A
Assessment Questions
4.
Why is peer review an important part of the
scientific process?
a. Peer review makes sure that the correct researcher
gets credit for discoveries.
b. Peer review helps identify errors or bias in
research.
c. Peer review is the system used to report
information to other scientists.
d. Peer review helps other scientists form theories
Assessment Questions
4.
Why is peer review an important part of the
scientific process?
a. Peer review makes sure that the correct researcher
gets credit for discoveries.
b. Peer review helps identify errors or bias in
research.
c. Peer review is the system used to report
information to other scientists.
d. Peer review helps other scientists form theories
ANS: B
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