What is Physical Science?

1. What is Physical Science? Chapter 1

2. Science • The study of the natural world. • To work like a scientist, you need to use the same skills that they do.

3. Skills Scientists Use • Observing • Inferring • Predicting

4. Observing • Using one or more of your senses to gather information • Sight • Sound • Touch • Taste • smell

5. 2 types of Observations • Qualitative: a description without numbers of measurements • Quantitative: observations using numbers or measurements • Examples:

6. Inferring • When you explain your observations • Inferences are based on what you already know. • Inferences are not always correct

7. Predicting • Making a statement about the future • What you think will happen

8. Physical Science • The study of matter, energy, and the changes they undergo.

9. Matter • Anything that has mass and takes up space • Matter is all around you • What isn’t matter?

10. Energy • The ability to do work or cause a change

11. 2 Main Branches of Physical Science • Chemistry: the study of the properties of matter and how matter changes • Physics: The study of matter, energy, motion, and forces, and how they interact

12. Scientific Inquiry • The different ways that scientists study the natural world. • Scientific Inquiry is an ongoing process of discovery in science.

13. The Process of Inquiry • Scientific inquiry does not always occur in the same way, but certain processes are involved. • Posing questions • Developing hypotheses • Designing experiments • Collecting and interpreting data • Drawing conclusions • Communicating results and ideas

15. Posing Questions • When you want to learn more about a subject you can ask questions. • Scientific questions can be answered by making observations. • Scientific questions can’t answer questions based on opinions, values, or judgments.

16. Developing Hypotheses • Hypothesis is a possible answer to a scientific question. • It is a prediction that can be tested. • The data collected may or may not support the hypothesis.

17. Developing an Experiment • To test a hypothesis • Determine the parameters, which are factors that can be measured in the experiment • A well designed experiment only has one variable parameter that is intentionally changed • A controlled experiment: only one parameter is manipulated (changed) at a time.

18. Collecting and Interpreting Data • Data Table: an organized chart for recording observations • Data are the facts, figures and evidence collected during the experiment.

19. Collecting and Interpreting Data • Data can be explained after it is collected by graphing • Graphing can reveal patterns in the data

20. Drawing Conclusions • After scientists interpret the data, they conclude whether or not the data support the hypothesis.

21. Communicating • The sharing of ideas and conclusions with others through writing and speaking • Additionally, the design of the experiment is shared so that the procedures can be replicated and the results verified. • Communicating information often leads to more questions and ideas.

22. How Science Develops • Scientists use models and develop theories and laws to help people better understand the world.

23. Models • A model is a graphical representation of an object or process, like • Computer models • Mathematical equations • Pictures • 3D models

24. Scientific Theories • A well tested explanation for a wide range of observations or experimental results. • Theories attempt to explain “why” something happens • Theories have a large amount of supporting evidence. • Theories can be proved wrong

25. Scientific Laws • A statement that describes an observed pattern in nature without trying to explain it. • A scientific law is a statement that predicts what will happen every time with a given set of circumstances

26. Chapter 1.3 Measurement

27. Base Unit • a unit is a standard; an agreed-on quantity by which other quantities are measured • Always include units in your calculations and when reporting data/answers

28. SI: International System of units • A selection of metric units that the scientific community has agreed to use • SI Units: • Time is the second (s) • Length is the meter (m) • Mass is the kilogram (kg) • Volume is the cubic meter (m3) • But the cm3 and mL are commonly used

29. Volume of Rectangular Solids • Length x width x height • l x w x h

30. Volume of Irregular SolidsDetermining Volume by Water Displacement • 1) Read and record the initial volume of the water in the graduated cylinder (Vi) • 2) Place object in the graduated cylinder • 3) Read and record the final volume of the water (Vf) • 4) calculate the volume of the object (Vobj) • Vobj= Vf- Vi

31. Density • Density is a ratio that compares the mass of an object to its volume. • The units for density are often grams per cubic centimeter (g/cm3) or g/mL • Density = mass volume

32. Density example • If a sample of a metal has a mass of 13.9 g and a volume of 5.0 cm3, what is the density? • Density is a property that can be used to identify an unknown sample of matter. Every sample of pure aluminum has the same density.

33. Density Values • What is the identity of the sample in the previous problem?

34. Time • The SI unit of time is the second (s) • Longer increments of time can be measured in minutes or hours • Instruments that measure time are: • Clocks and stop watches • Conversion Factors: • 1 s= 1000 ms • 1 min= 60 s • 1 hr=60 min

35. Temperature • Celsius and kelvin scales • SI unit of Temperature is the kelvin (K) • Absolute Zero (0 K): The temperature at which all motion stops. There is no lower temperature • Instrument used to measure temperature: • thermometer

36. 1.4 Math and Science • Estimation: an approximation based on known information. It is not a “guess.” • Scientists use estimations when they can’t obtain exact numbers. • Accuracy: how close a measurement is to the true or actual value. • Precision or Reproducibility: how close several measurements are to one another. • Two or more measurements are needed.

37. ACCURACY VS. PRECISION Target 1 • Accurate Target 2: • Not accurate but reproducible

38. ACCURACY VS. PRECISION Target 1 • Accurate and reproducible Target 2: • Not accurate nor reproducible

39. Significant Figures • writing numbers to reflect precision in measurements and calculations • Significant figures in a measurement include all of the digits that have been measured exactly, plus one estimated digit.

40. Significant Figures

41. Sig Figs in Calculations ADDITION/SUBTRACTION • The answer has the same number of DECIMAL PLACES as the quantity with the fewest number of decimal places. Example 1Example 2 5.74 4.8 0.8231 - 3.965 + 2.651__

42. Sig Figs in Calculations, cont. Multiplication/Division • The answer has the same number of sig figs as the factor with the fewest significant figures • 5.02 x 89.665 x 0.10 = • 5.892 / 6.10 =

43. Sig Figs in Calculations

44. Sample Problem • What is the area of a ticket stub that measures 3.50 cm by 2.2 cm? Express the answer to the correct number of significant figures.

45. 1.5 Graphs in Science • Graphs represent data as a picture • They can reveal trends that you may not see from a data table

46. Line Graphs • Show the relationship between variables • Show how the responding variable changes in response to the manipulated variable

47. Plotting a Line Graph • Draw and label the axes. • x axis: manipulated variable • y axis: responding variable • Determine the scale…the spaces are of equal interval • Plot the data from the data table • Draw a line of best fit • A line that goes through the most points. Do not “connect the dots.” • Add a title: the title states the relationship between the variables or ID’s the variables A graph that yields a straight line is called a LINEAR GRAPH

48. Why a “Line of Best Fit?” • Errors in measurement occur, so not all the points will fall exactly on a straight line • By connecting the points, too much importance is placed on the individual points rather than on the general trend. • A “Line of Best Fit” emphasizes the overall trend shown by the data

49. Slope • Tells the change in y for every change in x • Slope = rise = y2-y1 run x2- x1 • To determine the slope: • choose any 2 points on the line • plug them into the slope formula • Calculate and include the units. This slope value is a constant. • y= kx can be used to calculate for an unknown value of y or x (k is the slope).