Chapter 1 Introduction to Science Section 1 The Nature of Science Section 2 The Way Science Works Section 3 Organizing Data
Skills Experiment Design SI Units and SI unit conversions Using graphs Scientific Notation and use in calculations Significant Digits
Objectives Section 1 The Nature of Science Describe the main branches of natural science and relate them to each other. Describe the relationship between science and technology. Distinguish between scientific laws and scientific theories. Explain the roles of models and mathematics in scientific theories and laws.
How Does Science Take Place? Scientists observe. Scientists investigate. Scientists plan experiments. Scientists always test the results.
How Does Science Take Place? continued Science is the knowledge gained by observing in order to discover facts and to formulate laws or principles that can be verified or tested. Social Science deals with individual and group behaviors. Natural Science deals with how the universe works. Biological science is the science of living things. Physical science is the science of matter and energy. Earth science is the science of the Earth, the atmosphere, and weather.
Natural Science
Physics
How Does Science Take Place? continued Science and technology work together. Some scientists practice pure science defined as the continuing search for scientific knowledge. Some scientists and engineers practice applied science defined as the search for ways to use scientific knowledge for practical applications. Technology is the application of science for practical purposes.
Scientific Laws and Theories Laws and theories are supported by experimental results. Scientific theories are always being questioned and examined. To be valid, a theory must: explain observations be repeatable be predictable
Scientific Laws and Theories, continued Scientific law a summary of many experimental results and observations; a law tells how things work what will happen Scientific theory an explanation for some phenomenon that is based on observation, experimentation, and reasoning
Comparing Theories and Laws
Scientific Laws and Theories, continued Mathematics can describe physical events. A qualitative statement describes something with words. A quantitative statement describes something with mathematical equations.
Scientific Laws and Theories, continued Theories and laws are always being tested. Models can represent physical events. A model is a representation of an object or event that can be studied to understand the real object or event. Scientists use physical and computer models to study objects and events.
Models
Physical, Mathematical, and Conceptual Models
Objectives Section 2 The Way Science Works Understand how to use critical thinking skills to solve problems. Describe the steps of the scientific method. Know some of the tools scientists use to investigate nature. Explain the objective of a consistent system of units, and identify the SI units for length, mass, and time. Identify what each common SI prefix represents, and convert measurements.
Science Skills Critical thinking is the ability and willingness to assess claims critically and to make judgments on the basis of objective and supported reasons, facts, and data.
Science Skills, continued Using the scientific method The scientific method is a general description of scientific thinking rather than an exact path for scientists to follow. Scientific method is a series of steps followed to solve problems; includes collecting data, formulating a hypothesis, testing the hypothesis, and stating conclusions
Scientific Method
Hypothesis
Science Skills, continued Hypothesis a possible explanation or answer that can be tested Variable a factor that changes in an experiment in order to test a hypothesis The values of the independent variable are set before the experiment takes place. The values of the dependent variable depend on what happens in the experiment.
Controlled Experiment Testing hypotheses Scientists test a hypothesis by doing a controlled experiment. In a controlled experiment, all the factors are kept constant except for one. A control is a standard for comparison.
Controlled Experiment continued
Science Skills, continued Conducting experiments No experiment is a failure The results of every experiment can be used to revise the hypothesis or plan tests of a different variable.
Experiment Design Assignment: Investigate the impact on plant growth of adding various amounts of fertilizer to potted plants. Think about what you would need to do to be certain that the fertilizer was having the impact on the plant growth.
Experiment Design, continued You perform an experiment and collect the data shown in the table below. 1. What was the independent variable? 2. What was the dependent variable? 3. What was the control? 4. Describe the overall trend. 5. What was held constant?
Units of Measurement SI units are used for consistency. Scientists use the International System of Units (SI) to make sharing data and calculations easier.
SI (Le Système Internationale d Unités)
Units of Measurement, continued SI prefixes are for very large and very small measurements.
Units of Measurement, continued
Math Skills Conversions A roll of copper wire contains 15 m of wire. What is the length of the wire in centimeters? Practice p.17
Units of Measurement, continued Length a measure of the straight-line distance between two points Mass a measure of the amount of matter in an object Volume a measure of the size of a body or region in three-dimensional space Weight a measure of the gravitational force exerted on an object
Volume
Section 3 Organizing Data Objectives Interpret line graphs, bar graphs, and pie charts. Use scientific notation and significant figures in problem solving. Understand the difference between precision and accuracy.
Presenting Scientific Data Line graphs are best for continuous change. Line graphs are usually made with the x-axis showing the independent variable and the y- axis showing the dependent variable.
Line Graph
Presenting Scientific Data, continued Bar graphs compare items. A bar graph is useful for comparing similar data for several individual items or events. A bar graph can make clearer how large or small the differences in individual values are.
Bar Graph
Presenting Scientific Data, continued Pie charts show parts of a whole. Data in a pie chart is usually presented as a percent.
Writing Numbers in Scientific Notation Scientific notation is expresses a quantity as a number multiplied by 10 to the appropriate power. 10 3 = 1000 10 2 = 100 10 1 = 10 10 0 = 1 10-1 = 0.1 10-2 = 0.01 10-3 = 0.001
Writing Numbers in Scientific Notation, continued Using scientific notation When you use scientific notation in calculations, you follow the math rules for powers of 10. When you add or subtract values they must all have the same power of 10. When you multiply two values in scientific notation, you add the powers of 10. When you divide, you subtract the powers of 10.
Math Skills Writing Scientific Notation The adult human heart pumps about 18 000 L of blood each day. Write this value in scientific notation. Practice p.23
Scientific Notation
Using Significant Figures Precision and accuracy Precision is the exactness of a measurement Accuracy is how close a measurement is to the true value of the quantity being measured Significant figures prescribe the number of decimal places retained in presented data-- based on the precision of the measurement
Accuracy and Precision, part 1
Accuracy and Precision, part 2
Accuracy and Precision
Using Significant Figures, continued When you use measurements in calculations, the answer is only as precise as the least precise measurement used in the calculation. The measurement with the fewest significant figures determines the number of significant figures that can be used in the answer.
Math Skills Significant Figures Calculate the volume of a room that is 3.125 m high, 4.25 m wide, and 5.75 m long. Write the answer with the correct number of significant figures. 1. List the given and unknown values. Given: length, l = 5.75 m width, w = 4.25 m height, h = 3.125 m Unknown: Volume, V =? m3
Math Skills, continued 2. Write the equation for volume. V=l w h 3. Insert the known values into the equation, and solve. V = 5.75 m 4.25 m 3.125 m V = 76.367 1875 m3 The answer should have three significant figures. V = 76.4 m3
Math Skills Using Scientific Notation Cushing plans to buy a rectangular tract of land measuring 7.36 x 103 m by 2.38 x 104 m to establish a nature preserve. What are the area and perimeter of this tract? 1. List the given and unknown values. length, l = 1.38 x 104 m width, w = 5.36 x 103 m Unknown: area, A =? m2 perimeter, P=? m Given:
Math Skills, continued 2. Write the useful relationships (equations). A = l w, P = 2l + 2w 3. Insert the known values into the equations, and solve. A = (2.38 104 m) (7.36 103 m); regroup A = (2.38 7.36) (104 103) (m m); add powers of 10 A = (2.38 7.36) (104+3) (m m) A = 17.5168 107 m2 A = 1.75 108 m2 P = 2(2.38 x 104 m) + 2(7.36 x 103 m) P = 4.76 x 104 m + 14.7 x 103 m; match powers of 10 P = 47.6 x 103 m + 14.7 x 103 m = 62.3 x 103 m P = 6.23 x 104 m Note: an exact number, e.g. 2, does not limit significant figures Practice p.24
Significant Figures Practice p.25, Math Skills p.26
TERMS length (x, l, h) mass (m) time (t) TOOLS (equations) (m) (kg) (s) Chapter Review p.28; 1-7, 13-19