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 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 = meter mass = gram volume = liter (fluid), = cm3 (solid) time = second temperature = Celsius   Base units are used with prefixes to describe large or small quantities Prefixes indicate multiples of ten

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: We know : 100𝑐𝑚 𝑚 or 1𝑚 100𝑐𝑚 , these are the conversion factors for possible use in solving this problem. We set the solution up as a multiplication problem using the conversion factor that will leave us with the unit of “meter” 350𝑐𝑚 1𝑚 100𝑐𝑚 = 350𝑐𝑚 𝑥 1𝑚 100𝑐𝑚 = 350𝑚 100 =𝟑.𝟓𝟎𝒎 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 Solution 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 Conversion factors for these units: 1000𝑔 1𝑘𝑔 , 1𝑘𝑔 1000𝑔 , 1𝑔 100𝑐𝑔 , and 100𝑐𝑔 1𝑔 Step 1: convert kilograms to grams 0.25𝑘𝑔 1000𝑔 1𝑘𝑔 = 0.25𝑘𝑔 𝑥1000𝑔 1𝑘𝑔 =250𝑔 Step 2: convert grams to centigrams 250𝑔 100𝑐𝑔 1𝑔 = 250𝑔 𝑥 100𝑐𝑔 1𝑔 =𝟐𝟓,𝟎𝟎𝟎𝒄𝒈 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

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.

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 Graphs Line 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.

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

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)

Section 4: Science and Technology Technology – 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?