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Pearson Prentice Hall Physical Science: Concepts in Action

Pearson Prentice Hall Physical Science: Concepts in Action. Chapter 1 Science Skills. 1.1 What is Science?. Objectives 1. Describe how the process of science starts and ends. 2. Explain the relationship between science and technology.

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Pearson Prentice Hall Physical Science: Concepts in Action

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  1. Pearson Prentice Hall Physical Science: Concepts in Action Chapter 1 Science Skills

  2. 1.1 What is Science? • Objectives • 1. Describe how the process of science starts and ends. • 2. Explain the relationship between science and technology. • 3. Describe the main branches of natural science and relate them to each other.

  3. Science involves asking questions about nature and then finding ways to answer them • These questions arise from the natural curiosity of human beings • Definition: science is a system of knowledge and the methods you use to find that knowledge

  4. How the Process Starts & Ends + Technology • Science begins with curiosity and often ends with discovery • Definition: technology is the use of knowledge to solve practical problems • Science and technology depend on each other- advances in one lead to advances in the other

  5. Branches • Natural science is divided into 3 branches: physical science, Earth & space sci, and life sci • Phys sci has 2 main branches: chemistry & physics • Definition: chemistry is the study of composition, structure, properties & reactions of matter • Definition: physics is the study of matter & energy, and the interactions between the two through forces & motion

  6. Chemistry & physics are applied to study the Earth • The foundation of earth sci is geology • Definition: geology is the study of the origin, history & structure of Earth • Geology focuses Earth’s rocks

  7. Astronomy is the foundation of space sci • Definition: astronomy is the study of the universe beyond Earth • It includes the sun, moon & stars • Our study of physical science will include chemistry, physics, Earth and space sciences

  8. Life science is the 3rd branch of natural science • It is also called biology • Definition: biology is the study of living things • We will not focus on biology in this class although certain aspects of it may come up from time to time • This class will focus on matter & change, space & time, forces, motion & energy

  9. 1.2 Using a Scientific Approach • Objectives: • 1. Explain the goal of the scientific method • 2. Define how scientific law differs from scientific theory • 3. Explain why scientific models are useful • 4. Analyze why it is important to follow instructions and directions exactly in science.

  10. Goal of the Method • Definition: scientific method is an organized plan for gathering, organizing and communicating information • The goal of any sci method is to solve a problem or to better understand an observed event

  11. There are several steps to using the sci method: • 1. make an observation- definition: an observation is information you obtain through your senses • 2. ask a question from the observation • 3. develop a hypothesis- definition: a hypothesis is a proposed answer to the question based on an educated guess

  12. A. the hypothesis must be testable in order to be useful • 4. test the hypothesis by performing an experiment • A. definition- a controlled experiment is an experiment where only one variable (the manipulated variable) is changed at a time • B. definition: a variable is a piece of data or a condition that can change

  13. C. definition: a manipulated variable is a condition (temp, speed, etc.) that causes a change in another condition • D. definition: responding variable is the variable that changed • 5. collect (and record) data on the responding variable • 6. analyze the data usually with graphs, charts or mathematical interpretations

  14. 7. draw conclusions from the analysis • A. if the hypothesis is not supported (notice you do not say the hypothesis is “wrong”!), revise the hypothesis and do a different experiment to test the new hypothesis • B. If the hypothesis is supported (the hypothesis is not “right” or “correct”, it is supported), develop a theory

  15. Scientific Theory • 8. develop a theory- definition: a scientific theory is a well tested explanation for a set of observations or experimental results • A. a theory is not possible for just one experiment- the results must be reproducible by you and many other scientists • B. theories are never proved, but become stronger if facts continue to support them & revised or dropped if new facts & discoveries occur

  16. Scientific Law • Definition: scientific law is a statement that summarizes a pattern found in nature • It occurs after repeated observations or experiments • A sci law does not explain an observed pattern in nature • A sci law only describes the pattern • The explanation of the pattern comes from sci theory

  17. Following Directions • Definition: a model is a representation of an object or event • A scientific model makes it easier to understand thing that might be difficult to observe directly • Safety is very important in science • Scientists use “STANDARD PRECATIONS” when working with difficult or dangerous materials • ALWAYS FOLLOW DIRECTIONS AND INSTRUCTIONS EXACTLY WHEN PERFORMING ANY SCIENTIFIC ANALYSIS

  18. 1.3 Measurement • Objectives: • 1. Analyze why scientific notation is useful • 2. Define the units that scientists use for their measurements • 3. Explain precision and accuracy

  19. Usefulness of Sci Notation • Scientific notation expresses a value by using a number between 1 & 10 (the coefficient), & a power of 10 • Sci notation makes very large or very small numbers easier to work with

  20. Practice with Scientific notation • 1. write the number 3,000,000 in scientific notation • A: 3 x 106 • 2. write the number 0.000006 in scientific notation • A: 6 x 10-5

  21. When dividing numbers written in sci notation, divide the coefficients and subtract the exponents • 4. Calculate how far light travels in 8.65 x 104 seconds if the speed of light is 3.0 x 108 m/s • A: The problem asks how FAR, so the answer is in METERS • A: 8.65/ 3.0 = 2.88 • 104/108 = 10-4, So 2.88 x 10-4

  22. When multiplying numbers in sci notation, multiply the coefficients and add exponents • 3. Perform the calculation. Express your answer in sci notation: • (7.6 x 10-4m) x (1.5 x 107m) • A: 7.6 x 1.5 = 11.4 • 10-4 x 107 = 103 • 11.4 x 103 = 1.14 x 104

  23. Units & Conversions • You will also learn how to use the exponent function on your calculator in this class • SI units are the international system of units used by scientists to measure • Seven metric units are the base units given in tables that follow- you must know these • You must also know the metric prefixes that describe how large the numbers are

  24. Definition: a conversion factor is a ratio of equivalent measurements that converts a quantity expressed in one unit to another unit • Problem: Express 8848 meters in kilometers • A: 1 kilometer = 1000 meters, so they are a ratio: 1 km/1000m OR 1000m/1km

  25. Since the ratio are numbers that are equal to each other, it is a way to express the number 1 • You may use the mathematical trick of cross cancellation in deciding which ratio to use • A:8848m x 1 km/1000m =8.848km • To convert back to meters, use this setup: • 8.848km x 1000m/1km=8848m • In this setup the km cancels

  26. Density • Density is an object’s mass divided by its volume • Density = mass/volume • The units for mass are usually grams • The units for volume are either cm3 or mL • Notice that neither measurement is a base unit, but a combination of derived and SI prefixes

  27. Let’s practice density: • The mass of a piece of iron is 34.73 g. The volumes is 4.42 cubic centimeters. What is its density? • A:34.73g/4.42cm3 = 7.85 g/cm3 • Try this one: The density of an object is 4.32 g/cm3. If the mass of the object is 8.64 g, what is the volume?

  28. What are you looking for? • A: volume • What units will your answer have? • A: cm3 • The density is expressed as a volume and can be thought of as a conversion factor, so it can be expressed as either 4.32 g/cm3 or 1cm3/4.32g • You need to cross cancel, so which ratio will you use to set up your problem where you must find cm3?

  29. A: Use 1cm3/4.32g and set up the problem this way: • 8.64 g x 1cm3/4.32g = 2 cm3 • Notice that when you set up the problem this way, the grams will cross cancel and you will be able to find the volume (which is cm3) • Special note: 1 mL = 1 cm3, so these units can be used interchangeably • If you have a liquid, you should use mL for the volume to express density

  30. Precision, Accuracy, Sig Figs & Temperature Measurement • Precision is how exact a measurement is • This means that if you tested the object 5 times, you would get close to the same answer 5 times • Accuracy is how close to the true measurement the result is

  31. The precision of a calculated answer is limited by the least precise calculation • The least precise calculation has the fewest significant figures

  32. Significant Figures • Significant figures are some-times called sig figs (slang) • Significant figures are all the digits that are known in a measurement, plus the last digit is estimated • 5.25 min has 3 sig figs, 5 min has 1 sig fig and so on • Answers to calculations should only have the same number of figures as the least precise measurement

  33. For example: density = 34.73g/4.42cm3=7.857466g/cm3 • The answer should only have 3 significant figures because the volume (4.42 cm3) has 3 sig figs • In this case, the volume is the least precise measurement and the answer should be rounded to 7.86 g/cm3

  34. Temperature Conversions • Definition: thermometer- instrument that measures temperature or how hot an object is • There are 3 temperature scales to convert back and forth from

  35. The scales are Fahrenheit, Celsius (also called centigrade) & Kelvin • More on the temperature scales later, but for now, here are the conversions:

  36. Practice a temperature conversion: Convert -11ºF into degrees Celsius and then into kelvins (notice that you do not use “degrees” with the Kelvin scale) • A: first go from ºF to ºC • (-11 – 32)= -43 • -43 x 5/9= -24ºC • -24ºC + 273 = 249 K

  37. 1.4 Presenting Scientific Data • Objectives: • 1. Explain how scientists organize data • 2. Explain how scientists communicate experimental data.

  38. Scientists use data tables and graphs • Data tables can list all sorts of observations • Line graphs are also used • The steepness of the line is called the slope • Slope = rise/run

  39. Scientists have a variety of ways they communicate with each other • They can … • write in scientific journals • Speak at conferences • Email one another • Produce websites • Converse

  40. Definition: a direct proportion is a relationship in which the ratio (division) between 2 variables is constant • Definition: an inverse proportion is the relationship in which the product (multiplication) between 2 variables is constant • Bar graphs compare sets of measurements • Circle graphs or pie charts show how a part of something relates to the whole usually as a percentage

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