Physical Science

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 group________________________________ • Test Group__________________________________

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.

Physical Science