Physical ScienceCh. 1 “Introduction To Science”

Ch. 1 Section 1 Notes

“The Nature of Science”

How Science Takes Place

• Turn to page 5

• A scientist may perform experiments to find a new aspect of the natural world, to explain a known phenomenon, to check the results of other experiments, or to test the predictions of current theories.

How science takes place

• Scientists answer questions by investigating.

• Scientists plan experiments

• Scientists observe

• Scientists always confirm results.

Wilhelm Roentgen

• Found that the cathode rays passed through almost everything, but dense materials absorbed some of the rays.

• He published his findings and called them X rays. (x represents an unknown in a mathematical equation.)

• 3 months later, another doctor used his discovery to set the bones in a boy’s arm.

• In 1901, Roentgen received the first Nobel Prize in physics for his discovery.

The Branches of Science

• Science is observing, studying, and experimenting to find the nature of things.

Science can be broken down into two main categories:

– Social science (deals with individual and group human behavior)

– Natural science (tries to understand how “nature,” or “the whole universe” behaves.

• Most of the time, natural science is divided into biological science, physical science, and Earth science.

– Look at Figure 3 on page 7

• The branches of science work together

• Science and technology work together. -Technology is the application of science for practical uses.

Scientific Laws and Theories

• Theories explain why something happens, and laws describe how something works.

– A scientific law describes a process in nature that can be tested by repeated experiments. A law allows predictions to be made about how a system will behave under a wide range of conditions.

• It does NOT explain how a process takes place.

Theory

• A theory gives an explanation of how a natural process works

To be valid, a theory must pass several tests:

– A theory must explain observations clearly and consistently.

– Experiments that illustrate the theory must be repeatable.

– You must be able to predict the results from the theory.

Mathematics can describe physical events

• Qualitative vs. Quantitative

• Universal gravitation equation:– F=G m(1) x m(2) / d x d

Models

• Computer models– Meteorologists use it to help forecast the

weather.

• Water molecule models

• Atom molecule models

• Etc.

1.1 Homework

• 1.1 Concept Review

• 1.1 Review page 12 #s 1-3, 5 & 6

Ch. 1 Section 2 Notes

• Turn to page 14

• The Way Science Works

Science Skills

• Identifying problems, planning experiments, recording observations, and correctly reporting data are some of the most important science skills.– The most important skill is learning to think

creatively and critically.

Critical thinking helps you solve problems logically.

• If you approach a problem by asking questions, making observations, and using logic, you are using critical thinking. – How much is the big bag?– How much is the small bag?– How many ounces are in each?– Etc.

A. Science Skills

1. Critical thinking—applying logic and reason; objective; consider all factors; analyze

2. Using the scientific method—series of logical steps to solve problems

a. ask questions, gather info, form hypothesis

Scientists use scientific methods to solve problems.

• Scientific methods are general ways to help organize your thinking about questions.

• Scientific methods are sets of procedures that scientists use, but the steps may vary– Look at Figure 2 Pg. 15

• Most scientific questions begin with observation. Then, they are usually followed by a hypothesis.

• QUESTION:– Do you have to use exactly the same steps every

time that you use a scientific method?

Scientists test hypotheses.

• A hypothesis is tested by doing a controlled experiment.

• In a controlled experiment: – Variables that can affect the outcome of the

experiment are kept constant, or controlled, except for the one that you want to measure.

– Only the results of changing the given variables are observed.

• It is best to only change one thing at a time to test the hypothesis. This will make it easier to reach your conclusion.

3. test hypothesis

a. a good experiment tests only one variable at a time

i. if more than one were tested, you wouldn’t know which one caused the change

b. variable—anything that can change

Experiments test ideas.

4. Conducting experiments

a. no experiment is a failure

b. scientists use results to revise hypothesis and plan new experiments

c. always keep question being tested in mind

d. sometimes scientists must make observations and use models instead of experiments

5. Using scientific tools

a. Observation

i. Senses

ii. Microscopes

iii. Telescopes

iv. Spectrophotometers

v. Particle accelerators

B. Units of MeasurementSI—Systeme Internationale

1. SI units are used for consistencya. based on metric systemb. 7 base units

2. SI prefixes are added for very large or small numbers

Basic units in SI and metric Length—meter—mMass—gram—gTime—second—sTemp—Kelvin—KCurrent—ampere—ASubstance—mole—molLumination—candela—cd

Giga- G 109 1 000 000 000

Mega- M 106 1 000 000

kilo- k 103 1000

hecto- h 102 100

deka- da 10 10

Basic unit (m, l, g) 1 1

SI and metric prefixes

deci- d 10-1 0.1

centi- c 10-2 0.01

milli- m 10-3 0.001

micro- u (mu) 10-6 0.000 001

nano- n 10-9 0.000 000 001

pico- p 10-12 0.000 000 000 001

SI and metric prefixes

3. Making measurements (pp. 18-19)

i. length—distance between 2 points

unit: use:

ii. mass—quantity of matter

unit: use:

iii. volume—space; capacity

unit: use:

iv. weight—force of gravity on object;

not really used in SI

unit: use:

1.2 Homework

• 1.2 Concept Review

• 1.2 Review page 21 #s 1-5, 9 & 10

Ch. 1 Section 3 Notes

• Turn to page 22

• Organizing Data

1.3 Organizing DataA. Presenting scientific data

1. line graph—shows continuous changes

2. bar graph—compares items

3. pie graph—shows parts of a whole

B. Scientific Notation—a simple number x a power of ten1. the exponent (power)

tells how many places to move decimal

2. positive—move right; negative—move left

4 x 107 =

3.7 x 10-8 =

6.23 x 109 =

3.04 x 10-6 =

300,000,000,000 =

0.000 000 02 =

652,070,000,000,000 =

0.000 000 003 074 =

C. Significant figures—the digits in a measurement that are known with certainty

How many significant figures?

1.58 ____2.0 ___7000 ___2.09 ___60830 ___

1. precision—how close measurements are to each other

-the degree of exactness-smaller measurements

are more precise

2. accuracy—how close a measurement is to the true value

1.3 Homework

• 1.3 Concept Review

• 1.3 Review #s 1-7 page 28