Chapter 1: The Nature of Science

•Section 1: The Methods of Science

•Section 2: Standards of Measurement

•Section 3: Communicating with Graphs

•Section 4: Science and Technology

Section 1: The Methods of Science

• What is science?

Science is a process that uses observation and investigation to gain knowledge about events in nature

Science explains nature – science helps you understand the natural world

Scientists learn about the natural world by performing investigations

Investigations can be field studies or lab experiments

Section 1: The Methods of Science

Based on Mjnew information Mj

gathered Mj

The Scientific Method Mj

State Problem Mjor Mj

Ask Question Mj

Research Mj What is already known Mjabout problem/question Mj

Form Hypothesis MjA possible solution Mj

or answer Mj

Test Hypothesis Mj

Form Conclusion Mj

Control variables Mj

Collect Data Mj

Analyze Data Mj

Hypothesis MjSupported Mj

Hypothesis MjNot Supported Mj

Communicate Results Mj

The Scientific Method

• An organized problem solving procedure

• Must have a specific question or problem

• Depending on the nature of the investigation, not all steps need to be used

• Communicating the results of the investigation is a critical part of science. It allows others to test and confirm your results.

• Vocabulary: hypothesis, variable, dependent variable, independent variable, constant, control

Section 1: The Methods of Science

Scientific Theories and Laws

• Scientific theory – an explanation of things or events based on knowledge gained from observations and investigations

Examples: Einstein’s Theory of Relativity, Darwin’s Theory of Evolution

• Scientific law – a statement about what happens in nature and that seems true all the time.

Example: The Law of Universal Gravitation

A scientific law never explains why or how the law is true

Science and Technology

• Technology – the application of science to help people

• Generally, scientific knowledge comes before the application of that knowledge

Example: Experiments that showed light behaves as a particle (photon) occurred in the early 1900’s, today applications of this knowledge include CD players and laser scanners

• Think about these questions:

Do science and technology always produce positive results?

Is a new technology always embraced by end users (people like you)?

Section 2: Standards of Measurement

The Metric System

• Known as the International System of Units or SI

• SI base units: distance = metermass = gramvolume = liter (fluid), = cm3 (solid)time = secondtemperature = Celsius

• Base units are used with prefixes to describe large or small quantitiesPrefixes indicate multiples of ten

Base Units Mj(grams, meters, liters) Mj

milli Mjm Mj

1/1,000 Mj

centi Mjc Mj

1/100 Mj

hecto Mjh Mj

100 Mj

deka Mjda Mj10 Mj

deci Mjd Mj

1/10 Mj

many base units = 1 of thes Mje Mj

kilo Mjk Mj

1,000 Mj

fractions Mj

multiples Mj

many of these = 1 base uni Mjt Mj

Section 2: Standards of Measurement

Converting Between Units

• A powerful problem solving tool called “Dimensional Analysis” guides a student to the correct solution to a problem

Example 1: 350-cm = ?-m

Solution:1. We know : or , these are the conversion factors for possible

use in solving this problem.

2. We set the solution up as a multiplication problem using the conversion factor that will leave us with the unit of “meter”

3. Notice that the “cm” units cancel, and the unit remaining in the problem is meters, “m”. That is the dimensional analysis for this problem.

Hint: Always set up the problem so that the unit you are solving for is in the numerator of the conversion factor and the unit you want to get rid of is in the denominator of the factor.

Section 2: Standards of Measurement

Converting Between Units (cont.)

Example 2: 0.25kg = ? cg

Solution1. There is no direct relationship between kilograms and

centigrams, so the solution requires two steps – converting kilograms to grams and then converting grams to centigrams

2. Conversion factors for these units: , , , and

3. Step 1: convert kilograms to grams

4. Step 2: convert grams to centigrams

Notice that using the correct conversion factor and doing the dimensional analysis makes solving this difficult problem fairly easy.

Section 2: Standards of Measurement

Density

Density is the mass per unit volume of a material• Mass is the amount of matter in an object

• Volume is the amount of space an object occupies• Volume of a liquid is measured in liters• Volume of a solid is measured in meters3 (or some

multiple)

• Different materials can have the same mass but different densities

• The density of a substance can help identify the substance

• The equation for density:

• Typically, the unit for density will be g/cm3 or g/L

𝝆= 𝒎𝑽 Where: ρ =density

m = mass V = volume

Section 2: Standards of Measurement

Example: A block of wood 5 cm x 7.5 cm x 2.5 cm has a mass of 150 g. What is the density of the wood block?

Solution:

Your solution must include the following:• A list of the known variables and what you are solving for• The equation(s) used to solve the problem• All work and dimensional analysis.

l=5.0 cm w =7.5 cm h =2.5 cm m = 150g ρ =?

V = l x w x h = 5.0cm x 7.5cm x 2.5 cm V = 93.75 cm3

𝜌= 𝑚𝑉= 150𝑔93.75𝑐𝑚3 = 𝟏.𝟔𝟎 𝒈𝒄𝒎𝟑

Section 3: Communicating with Graphs

Many experiments and investigations result in the accumulation of a large quantity of numerical data. This data must be organized before it can be used to make any conclusions.

Graphs are used to organize numerical data.

There are three basic types of graphs:• Line graphs• Bar graphs• Pie graphs

Section 3: Communicating with GraphsLine graphs – Show the relationship where the dependent variable changes as the independent variable changes• Dependent variable – factor that changes as the independent

variable changes• Independent variable – factor that, as it changes, affects the

measure of another variable• To create a line graph:

1. Determine which of the variables is the dependent variable and which in the independent variable 2. Draw and label the x- and y-axis, placing the independent variable on the x-axis and the dependent variable on the y-axis 3. Plot the coordinates 4. Connect the points

Example: A lab assignment is to measure the change in water temperature over time as heat is applied to the water. The following data was collected. Graph the data.

time temp 0s 20oC

30s 22 60s 31 90s 40

120s 48 150s 56 180s 70 210s 82 240s 100

Section 3: Communicating with Graphs

Bar graph – useful for comparing information by counting

Example: The results of the first test are summarized in the table below. Graph the results

grade # students A 1 A- 2 B+ 2 B 4 B- 3 C+ 4 C 3 C- 3 D+ 2 D 1 D- 1 F 1

Section 3: Communicating with Graphs

Pie graphs – used for comparing parts of a fixed quantity

• To create a pie graph:• calculate % of total of each part• 360o in a circle• apply % to 360o

• measure, draw, and label graph

Example: Comparing the class sizes at Spearfish High School (total enrollment is 600 students)

Grade # of

Students Freshman 100

Sophomores 150 Juniors 180 Seniors 170

Section 4: Science and TechnologyTechnology – the application of scientific knowledge to benefit people. Can be:• Any human made object• Methods or techniques for making any object or tool• Knowledge or skills needed to operate a human-made object• A system of people and objects used to do a particular task Society and Technology• Society affects how new technologies develop:

• If people support a new technology that technology will continue to be developed

• Example: Alternative fuel automobiles, why is this technology being developed now instead of 40 years ago?

Economics and technology• Development of new technologies is funded by different sources

including state and federal governments, private foundations, and private industries

Ethics and technology• Development of new technologies can pose ethical problems

about their use• Example: The development of the atom bomb. Good thing:

dropping the bombs shorten the war and prevented thousands of U.S. casualties. Bad thing: Resulted in the proliferation of nuclear bombs.

What are some moral or ethical issues that must be considered as new technologies are developed?