Methods of Science What is science?  method for studying the natural world  different types of sciences life science, earth science, and physical science How do scientists learn about the world?  investigations (observations, experiments, models)

Methods of Science we need science to help understand the natural world  done through investigations & building models  sometimes needs to be modified insert Fig. 2 – pg. 7

Methods of Science often scientists follow certain steps to find out information use the Scientific Method – a pattern of investigation procedures (six steps)  State the Problem  Gather Information  Form a Hypothesis  Test the Hypothesis  Analyze Data  Draw Conclusion Figure 2 – pg. 8

Scientific Method State the Problem state what is going to be investigated wonder ‘Why?’ ‘What?’ ‘How?’ Research & Gather Information first need to figure out what is already known about the problem Form a Hypothesis hypothesis – a possible explanation for a problem using what you know & what you observe

Scientific Method Test a Hypothesis done by making observations or by building a model or doing an experiment experiment – organized procedure for testing a hypothesis; tests the effect of one thing on another (variables) under controlled conditions variable – a quantity that can have more than a single value  dependent variable  independent variable  constant  control

Scientific Method Analyze Data recording observations organizing the test data into tables & graphs Drawing Conclusions a judgment based on the information obtained from the experiment hypothesis is supported or discarded  if supported, experiments must be repeated to validate  if not supported, the hypothesis must be revised

Scientific Method Experiment variables independent variable – the value that the experimenter changes to see how it will affect others dependent variable – the value that changes according to the changes in other variables constant – a factor that does not change control – the standard by which the test results can be compared

Scientific Method State the Problem Research & Gather Information Form a Hypothesis Test Hypothesis Analyze Data Draw Conclusions Hypothesis FalseHypothesis True Repeat experiment to make sure hypothesis is true. Come up with new hypothesis.

Scientific Method example: Sponge Bob notices that his pal Gary is suffering from slimotosis, which occurs when the shell develops a nasty slime and gives off a horrible odor. His friend Patrick tells him that rubbing seaweed on the shell is the perfect cure, while Sandy says that drinking Dr. Kelp will be a better cure. Sponge Bob decides to test this cure by rubbing Gary with seaweed for 1 week and having him drink Dr. Kelp. After a week of treatment, the slime is gone and Gary’s shell smells better. What was the initial observation? What is the independent variable? What is the dependent variable? What should Sponge Bob’s conclusion be?

Scientific Method example: Use the steps of the Scientific Method to explain this observation: A steel wool soap pad eventually becomes rusty after you use it several times (make sure to list the steps).

Models models are used when something is too large, too small to see, too complex, or too dangerous model – represents an idea, event, or object to help people understand it Can you think of any examples?

Theory & Law scientific theory – an explanation of things or events based on knowledge gained from many observations & investigations over time scientific law – a statement about what happens in nature & that seems to be true all the time a law tells what happens, a theory is the attempt to explain why it happens

Standards of Measurement when we measure things we need to have a standard standard – an exact quantity that people agree to use to compare measurements  examples: inch, foot, yard Why do you think we need standards?

Measurement measurements need to have a number & a unit the unit part of the measurement tells what scale or standard is used (way for everyone to understand the same thing)  in science there are units that everyone uses in 1960, an internationally agreed upon system of measurements was set up based on the metric system – The international system of units (SI Units)

Quantity Measured UnitSymbol Lengthmeterm Masskilogramkg Timeseconds Electric CurrentampereA TemperaturekelvinK Amount of Substance molemol Intensity of Lightcandelacd Measurement Systems need to have base units (something that is based on an object or event in the physical world) Table 2 – Pg. 15

Measurement Systems use prefixes to change the sizes of the units  metric system is based on units of 10  so prefixes are based on factors of 10  ex: prefix kilo- means one thousand, so 1 km = 1000 m  ex: prefix milli- means one-thousandth, so 1 mm = m  key to remember that 1000 g = 1 kg, 1 g = 1000 mg PrefixSymbolMultiplying Factor Kilo-k1,000 Deci-d0.1 Centic0.01 Milli-m0.001 Micro-μ Nano-n Table 3 – Pg. 15

Standards of Measurement Measuring Length length is the distance between 2 points SI Unit for length is the meter (m) Figure 10 – pg. 16

Standards of Measurement Measuring Volume volume – the amount of space occupied by an object for a solid rectangle, use V = l × w × h so units could be m 3 or cm 3 for liquids, 1 mL = 1 cm 3

Standards of Measurement Measuring Mass & Density matter – anything that takes up space & has mass mass – a measurement of the quantity of matter in an object density – the mass per unit volume of an object Density = mass ÷ volume  common units for density grams per cubic centimeter (g/cm 3 ) for solids grams per milliliter (g/mL) for liquids & gases insert Table 4 – pg. 18

WeightWW Wweight vs mass

Mass VS Weight _____________ never changes because it is detemined by the mtter in an object _______________ could change, because it is determined by the gravitational pull (gravity) on an object.

___Mass__________ never changes because it is detemined by the matter in an object ___Weight____________ could change, because it is determined by the gravitational pull (gravity) on an object.

Standards of Measurement Measuring Time & Temperature SI Unit for time is the second (s) SI Unit for temperature is the kelvin (K) 0 K is the point where there is virtually no particle motion or kinetic energy (absolute zero) other temp scales are Celsius & Fahrenheit

Standards of Measurement

converting between Celsius & Kelvin T °C = T K or T °C = T K – 273

Temperature Conversion Example: The boiling point of water at the top of Mt. Everest is 70°C. Convert this temperature to the Kelvin scale. T °C = T K 70°C = T K T K = 343 K

A book has a mass of 2000g and 10cm 3 of volume. What is its density? D=m/v =2000g/10cm 3 =200g/cm 3

Temperature Conversion Example: Liquid nitrogen boils at 77 K. What is the boiling point of nitrogen on the Celsius scale? T °C = T K 77 K – 273 = T °C T °C = –196°C T °C = T K – 273

Communicating with Graphs once you have data you need a way to analyze it graph – a visual display of data that makes trends easier to see than in a table need to choose scales appropriately (readability) Types of Graphs 1) line graph 2) bar graph 3) circle graph

Communicating with Graphs horizontal axis is called the x–axis  this is where the independent variable goes vertical axis is called the y–axis  this is where the dependent variable goes

Types of Graphs Line Graphs show relationships when dependent variable changes because changes in the independent variable used mainly with changes over time  choose appropriate scales  make sure x-axis is independent variable & y-axis is dependent variable  make sure units are consistent  use best-fit line or curve with data points  insert Fig. 15 – pg. 23

Communicating with Graphs Bar Graphs used to compare information or display data that does not change continuously (data collected by counting)  show how quantities vary across categories  make sure x-axis is independent variable & y-axis is dependent variable  insert Fig. 16 – pg. 24

Communicating with Graphs Circle Graphs (Pie Charts) shows how some fixed quantity is broken into parts  labeled as percents totaling up to 100% Figure 17 – pg. 25

Science & Technology How would you define technology? technology – the application of scientific knowledge to benefit people & society society – a group of people that share similar values & beliefs  society can affect how new technologies develop