Transcript Physical Science - Pleasant Hill Elementary School

Physical Science
Ch. 1: The Nature
of Science
Physical Science
 Physical science is the study of matter
and energy.
 Matter - mass, density, state of matter,
elements, compounds
 Energy - force, motion, sound, light,
kinetic and potential energy, electricity
• Science in general can be categorized as
either pure science or applied science.
• Pure science is the gathering or
discovery of new information.
• For example, when the laser was
created, that was brand new
information.
• Applied science (technology) is
where the pure science is taken
and put to a practical use.
• What are some examples of how
the laser (pure science) was put
to a practical use?
Practice
• Along with your
partner, come up with
1 good example of
pure science and
how it was turned into
applied science.
• Oftentimes, whether we're discovering new
information, trying to put it to a practical use,
or just going through our daily lives,
problems occur that must be solved before
we can move on.
There are numerous ways to solve almost
every problem. One of the most effective
techniques is to use the scientific method of
problem solving.
Scientific Method of Problem Solving

The scientific method is a 6 step
procedure which should take you from the
introduction of a problem through the
solution to the problem.
Step 1: Identify the problem
Step 2: Gather as much information about
the problem as possible.
Step 3: Form a hypothesis as to the solution
of the problem.
A hypothesis is a testable prediction.
Step 4: Test the hypothesis. This is done
through experimentation.
Step 5: Analyze information and data.
Step 6: Draw a conclusion
Was the problem solved or not?
If the problem was not solved, then you
must go back to a certain step. Which
one?
Solutions to a Problem
 Sometimes,
a solution must be
re-tested in order to insure that it
is truly a correct solution.
 For
example, if a new drug is
reported to cure a certain form
of cancer, then it will surely be
tested and re-tested to determine
if it truly is a cure.
Practice Problem
As a particular part of town
continues to grow, there is
an intersection in that area
which is having an
abnormally large number of
traffic accidents. Use the
scientific method to solve
the problem.
• Your cat has a litter of 4 kittens. After 1
month, 3 of the kittens are normal sized
while the 4th is noticeably smaller than the
others.
Come up with 3 hypotheses as to why this
may be, and tell how you could test each
hypothesis.
Experiments
• In order to test a hypothesis (step 4), it is
often necessary to conduct an experiment.
• An experiment is an organized procedure for
testing a hypothesis.
• The are 5 different parts to an experiment.



A good experiment has both an
independent variable and a dependent
variable.
An independent variable is what is being
tested. This variable is controlled by the
experimenter and changes between
groups.
A dependent variable is one whose value
depends on the independent variable.

For example, let's say a scientist
wants to conduct an experiment to
determine the effects of Ibuprofen
on intelligence.
He takes 2 groups of students,
giving 1 group 2 Ibuprofen tablets
a day for 4 weeks, while the other
group receives none. After the 4
week period, the scientist
administers an IQ test to both
groups.
The independent variable in this
experiment would be the Ibuprofen. That's
what is being tested, and what the
controller changes between the 2 groups.
What would be the dependent variable in
this experiment?

The group which is administered the
independent variable is called the test
group.

The other group was only there for
comparison to the test group. They are
called the control group.

Let's say that the Ibuprofen group
improved on their IQ test scores by an
average of 22 points. This would seem to
point to the fact that the Ibuprofen made
them smarter.
However......................

What if the IQ's of the
control group also rose
by 22 points?
It would appear then
that it was not the
Ibuprofen that made the
test group smarter, since
the other group got
smarter as well, without
taking Ibuprofen.



So that is why we have a control group, to
help us make more sense out of our
results.
The last things that a good experiment
needs are constants.
A constant is a variable that does not
change in an experiment.

For example, in the Ibuprofen experiment,
you would want to have certain things
stay the same between the 2 groups.
You would want:
- subjects who were about the same age
- about the same # of males and females
in each group
- subjects at about the same level of
intelligence.............etc.
• Let's set up a new experiment now.
• In 1998, Mark McGuire and Sammy Sosa
were in a race to see who would reach 61
home runs first.
• McGuire made it first, but not
without some controversy.
McGuire had been using the
drug androstenedione (andro),
which was legal at the time, but
has since become illegal.
Let's set up an experiment to
determine the effect of andro on
the homerun hitting ability of
major league players.

So having stated what the experiment will
test, what are the independent and
dependent variables going to be?
Independent Dependent -
Independent - Androstenedione
Dependent - The # of homeruns hit

Let's set up a test group and a control
group. What would we do to each?
Test -
Control -
Test - Takes 1 Andro tablet/day every day
from the first day of the season till the
last.
Control - Takes a placebo tablet every day
from the first day of the season till the
last.

Now let's determine some constants which
we should have. Let's get a minimum of 5.
1.
2.
3.
4.
5.

Now, with everything set up, we should be
able to compare the number of homers hit by
the members of each group during the season
and determine if Andro did indeed have an
effect. (Steps 4-6 in the Scientific Method)
• In the past 10 years, NFL teams have experienced
an abnormally high number of ACL (knee) injuries.
Recently a medical supply company has come out
with a new knee brace which they guarantee will
decrease ACL injuries by 50%.
• The league decides to test this new brace to see if
it works. One group of players is made to wear the
brace for the entire 2005 season, while another
group goes through the season without any type of
knee brace. Results are then compiled at the end
of the season.
• Independent variable
__________________________
• Dependent
variable___________________________
• Control
Observations & Inferences

As you progress through the
scientific method, you will gather
and evaluate different types of
information. When presented with
this information it is often necessary
to make observations and
inferences.

An observation is where you use your
senses to gather information.
For example:
- smelling milk to see if it's gone bad,
- watching you for your warning light to come
on to tell you that you're low on gas
- feeling around in your purse for your keys

An inference is a judgement based on
reasoning from evidence.
For example, inferring that:
-Since it is raining outside, softball practice
will be cancelled
-Because you studied hard for the test, you
will get a good grade
-Since the lights went out during the storm,
lightning must be to blame.
• Identify each of the following as either
observations or inferences:
– The Chiefs are a 7 pt. favorite over the Rams.
– The Chiefs will beat the Rams by 7 points.
– If the food is past the expiration date then you
will get sick if you eat it.
– The fielder made a very good play on the
groundball.
– It's very warm in this room.
Laws & Theories
Sometimes, more in-depth
experiments may actually
result in the formation of laws
or theories.
A law is a rule of nature.
Laws describe what
happens, but do not explain
why.
• What are some other
examples of laws?
A
theory is an explanation based on
observations and supported by
experimental results.
Models

A model is a system or
structure which represents
a particular concept or
object.

Models help us visualize objects and ideas
which are otherwise impossible or
impractical to see.