Physical Science
The Nature of Science
For this chapter there will be homework
assignments, a partner project, a vocabulary quiz, a
factor labeling quiz, and a chapter test.
Vocabulary:
Scientific Methods
Theory
Hypothesis
Scientific Law
Experiment
Standard
Variable
SI
Dependent Variable
Volume
Independent Variable
Matter
Constant
Mass
Control
Density
Bias
Graph
Model
Technology
Society
Notes:
Science is a method for studying the natural world,
it is a process based on inquiry that helps develop
explanations about events in nature.
Nature follows a set of rules, some simple and
others very complex. Scientists ask questions and
make observations to learn about the rules that
govern the natural world.
There are 3 main categories of science:
1. Life Science - deals with living things
2. Earth Science- investigates Earth and space
3. Physical Science- studies matter and energy
Often these three categories will overlap during a
scientific study. (ie. When studying how to build
better artificial limbs the scientist will look at
energy and matter (what materials to use) as well
as how muscles operate, so she is using both life
science and physical science.)
As scientists experiment they find explanations for
things in the natural world, however sometimes
these explanations have to be modified.
As we experiment and study more, we learn more
and we may find out that the information we had
was incomplete, or new technology we have may
provide more accurate information.
A great example of this is the Atom and its models.
4 Scientists, Dalton, Thomson, Rutherford, and Bohr
built off each other’s theories and models to get to
the model we use today!
https://www.youtube.com/watch?v=FxDpZ8wGgZ8
Investigations
Scientists learn new information about the natural
world by preforming investigations.
Some investigations involve observing something
that occurs and recording the observations. (in all
investigations accurate observations are VERY important)
Other investigations involve setting up experiments
with a control to test the effect of one thing on
another.
Some investigations involve building a model that
resembles something and then testing it to see how
it acts (like a car or plane model), or models that
represent process of objects that cannot be seen
with the naked eye (like the atom).
Scientific Method
Scientists do not always follow a rigid set of steps,
but investigations do follow a general pattern.
This pattern of investigation procedures is called
the scientific methods.
There are 6 common steps in the scientific
methods. Scientists can add or repeat steps, or even
skip steps, to accomidate their investigation.
Step 1:
State the problem:
Decide what you are going to investigate- Start
with a How or a Why question.
ie. Why does this happen?
Step 2:
Research & Gather Information:
Before starting an investigation you need to
find out what is already known about the problem.
Gather information from reliable sources! This
means not Wikipedia…
This information will help you to fine-tune your
question and move on to the next step…
Step 3:
Form a Hypothesis:
A hypothesis is a possible explanation for a
problem using what you know and what you
observe.
ie. I think this happens because….
Your hypothesis should be specific and testable!
Step 4:
Test your hypothesis:
You may be able to test your hypothesis by
making observations, or making a model and
relating it to real life situations.
The most common way to test a hypothesis is to
perform an experiment. An experiment tests the
effect of one thing on another using a control.
An experiment usually contains at least two
variables. A variable is a quantity that can have
more than a single value.
We use three different types of variables:
1. Independent Variable the variable that you
change to see how it will affect the dependent
variable.
2. Dependent Variable the value that changes
according to the changes in the other variables.
3. Constant a factor that does not change.
(Constants are very important- if I change two
variables I cannot tell which one affected the
dependent variable…)
4. Control the standard by which the test results
can be compared. Here you do not change the
independent variable, or keep conditions
‘normal’ for the situation.
Step 5:
Analyze the Data:
One of the most important parts of an
investigation is recording observations and
organizing the data into easy to read tables and
graphs.
When making observations you should record
all of the results, even the unexpected results.
These can be the most important results you get!
Step 6:
Draw conclusions:
Based on the analysis of the data, we then have
to decide whether the hypothesis is supported.
For a hypothesis to be accepted the experiment
must result in the same data every time it is
repeated.
If the hypothesis is not accepted you need to do
one of two things:
Either you need to revise your hypothesis
Or
You need to revise your experiment
It is important to remember to be objective in your
investigations. You should be careful to reduce the
bias in your work. Bias occurs when the scientist’s
expectations change how the results are analyzed
or the conclusions are made.
Example of bias:
http://frobinett.edublogs.org/2010/11/12/acouple-of-interesting-examples-of-bias/
Avoiding bias:
https://explorable.com/double-blind-experiment
Project: Scientific Method Lab!
Models:
Sometimes scientists cannot see everything that
they are testing, it may be too large, or too small.
The subject may take too much time to see
completely or be hazardous.
When these scenarios occur scientists use models.
A model represents an idea event or objective to
help people better understand it.
Scientific Laws and Theories
A scientific theory is an explanation of things or
events based on knowledge gained from many
observations and investigations. IT IS NOT A GUESS!
(in other subjects you may use theory as a guess or
an idea, “I have a theory that Miss Browne’s class is
going to be my favorite this year” but in science we
have to have evidence!)
A Scientific Law is a statement about what happens
in nature and that seems to be true all the time.
Like the Law of Gravity- objects with mass will be
attracted to Earth, things will always fall down.
(again, this in not like in other subjects, if you break
a law while driving you will get in trouble, you
cannot break a scientific law)
One more thing!
Science is awesome and can help you explain many
things about the world, but science cannot explain
or solve everything.
Questions about emotions or values are not
scientific, they cannot be tested. You may be able to
take a survey to gather opinions about these
questions, but you could not prove an opinion to be
true for everyone.
HW: p13 Section 1 Review # 1-3, p39 #40 Due____
Standards of Measurement
How do we use measurements on a daily basis?
What do we measure every day?
Suppose I want to know whether one of your desks
will fit through the doorway or not. You don’t have
a ruler, what can you use to measure?
How wide is the desk?
How wide is the doorway?
Will the desk fit through the doorway?
Can you be sure?
Even though you used the same body part to
measure (ie hand), you do not know that that your
hands are the same size. Since you did not use a
measurement standard, you cannot compare the
measurements.
A standard is an exact quantity that people agree to
use to compare measurements.
There are 2 main measurement systems that are
used worldwide. These systems are built on
standards that are universal.
System 1- The English system of measurement
This system is used in the United States.
Standards include feet, gallons, and pounds.
System 2- The metric system of measurement
This system is used by most other countries.
Standards are based on multiples of ten.
In 1960 the metric system was improved and
renamed the International System of Units or SI for
short. (I know the letters switched, it’s from the
French…silly French…)
All SI standards are universally accepted and
understood by scientists throughout the world.
The standard kilogram is kept in France, while the
standard meter equals the exact distance that light
travels through a vacuum in 1/299,792,458 seconds.
Every kilogram or meter used around the world
matches these standards!
Kilograms and meters are examples of base units. A
base unit in SI is one that is based on an object or
event in the real world.
There are 7 base units in SI and each has its own
symbol:
All other SI units are obtained from these SI units,
and that is done using prefixes.
The SI system is especially easy to use because it is
based on multiples of 10.
The prefixes are used with the names of the units to
indicate what multiple of 10 should be used with
the units…
Knowing these prefixes makes it easier to convert
between units!
We are going to use the Factor Label Method to do
this. You will use this method all year, as well as in
Chemistry and Physics, so please ask questions if
you don’t understand!
http://www.education.rec.ri.cmu.edu/roboticscurri
culum/vex_online/lessons/stall_torque/helpers/fac
tor_label.pdf
As a rule of thumb your problem set up should look
like this:
Desired Units
Starting Units x-------------------- = Desired Units
Starting Units
The in-between parts ^ are called
conversion factors.
Sometimes you will need to multiply by more than
one ratio to get to your desired units, you can do
this by using linking units. Your setup will look like
this:
Linking Units
Desired Units
Starting Units x-------------------- x -------------------- = Desired Units
Starting Units
Linking Units
Let’s Practice!
1. Your pencil is 11 cm long, how long is it in
millimeters?
2. How many seconds are in 2 years?
3. How many wheels are on 6 minivans?
4. How many liters are in 156.2 milliliters?
5. 9.85 meters are how many centimeters?
6. How many centimeters are in .456 kilometers?
7. How many seconds are in 3 days?
HW: Factor Label Worksheet! Due___________