Defining Physical Science

Transcription

1 Defining Physical Science

2 Defining Physical Science: Physical Science: The study of matter and energy A merging of two major braches of Science: 1. Chemistry: Study of the composition and changes of matter 2. Physics: Study of energy and laws of motion (i.e. the behavior of matter)

3 Advances in Physical Science: Advances first stem from a need, followed by inquiry. Science is the investigation of rational concepts capable of being tested by observation and experimentation. This analytical method distinguishes science from all other disciplines.

4 Advances in Physical Science: Scientists: Question natural phenomenon Observe the world around them. Read a variety of scientific books. Become science teachers. You are a scientist if you do any of these!

5 Advances in Physical Science: Basic Assumptions of Science: There is order in the universe. The human mind is capable of understanding it. Natural phenomenon is testable by experimentation that is repeatable. A real Scientist will attempt to answer their questions.

6 Scientific Method: The Scientific Method: A systematic approach to problem solving. 1. State the problem: Must first define the problem based on observation of a need. 2. Gather information on the problem: -- Leave no stones unturned The problem may already be solved at least partially.

7 Scientific Method: 3. Form A Hypothesis: A plausible prediction of the outcome of experimenting. - Use deductive reasoning (if/then statement) - e.g. If I use a fuel additive in my car, then it should improve its mileage. - Hypothesis are often stated as a question.

8 Scientific Method: 4. Experiment: Test the Hypothesis -Variable: One factor being tested. -Data: Information outcome of the experiment. Types of Data: 1. Quantitative: Numerical Data 2. Qualitative: Descriptive Data (color, behavior, etc)

9 Scientific Method: Must use a control set-up and experimental set-up. -The experimental set-up contains the variable to be tested, the control does not. -The control is the standard for comparison.

10 Scientific Method: 5. Record and Analyze data: -Use Accurate Measurements 6. State Conclusions: -Only after the experiment has been repeated to insure accuracy.

11 Scientific Method: Theory: The most logical explanation of events occuring in nature. Developed through repeated tests. Law: A repeatedly tested theory.. Generally accepted as true, but may be modified after further discoveries. Fact: The absolute truth.

12 Scientific Method In Practice: 1. The problem: A need to lower the freezing point of H 2 O to -10 C. 2. Information on the Problem: -H 2 O freezes at 0 C -Ethylene glycol freezes at -30 C 3. Hypothesis: One part ethylene glycol to 10 parts H 2 O will lower the freezing point to -10 C.

13 Scientific Method In Practice: 4. Experiment: Set up 6 replications of 1:10 ethylene glycol and H 2 O mixtures. Decrease Temperature.

14 Scientific Method In Practice: Data or Data Set 5. Record and Analyze Data Control: Experiment: H 2 O C H 2 O w/ 1/10 Ethylene Glycol X= 0-3 C

15 Scientific Method In Practice: 6. Conclusion: The freezing point of H 2 O with 1/10 ethylene glycol is -3 C. Caution: Never test more than one variable at a time. Use graphs to ease in interpreting data.

16 Temperature (C) Time of Freezing of H 2 O with 1/10 Ethylene glycol (antifreeze) Time (min) Temp C Time (min) Temp *Spaces between intervals on a graph must be equal. Q: Does this graph represent the control or experimental set-up?

17 Scientific Terms: Q: What does converge mean? A: Come Together Q: How would the temperature of a reacting substance be affected in an endothermic reaction? A: Temperature would go opposite of exothermic.

18 Scientific Measurements: Measurements must be accurate, reliable, and appropriate to the subject measured. Scientists use the metric or SI System (Système International d Unités).

19 Scientific Measurements: SI Base Units Derived Units Volume: Liter Weight: Newton Density: Gram/Liter Temperature: Celsius

20 Scientific Measurements: Length: Measure of distance 1 meter = 39.4 inches ( about 1 yard) = 100 centimeters = 1000 millimeteres 1000 meters = 1 kilometer Common tools for measuring length Meter Stick Metric Ruler Metric Tape Rolotape

21 Scientific Measurements: Metric prefixes, symbols, and multipliers Prefix Symbol Multiplier Exponential yotta Y 1,000,000,000,000,000,000,000, zetta Z 1,000,000,000,000,000,000, exa E 1,000,000,000,000,000, peta P 1,000,000,000,000, tera T 1,000,000,000, giga G 1,000,000, mega M 1,000, kilo k 1, hecto h deca da deci d centi c milli m micro µ nano n pico p femto f atto a zepto z yocto y

22 Scientific Measurments: Volume: Amount of space an object takes up Basic Unit: Liter (L) or Cubic Centimeter (cc or cm 3 ) Liters are usually used to measure liquid volume. cm 3 is usually used to measure solids. e.g. The volume of a box can be measured by length x width x heigth 1 cm 3 = 1 milliliter (1/1000 liter)

23 Scientific Measurments: How could you measure the volume of an irregular shaped object in liters? Liquid volume is measured using a graduated cylinder. Measurements are read at the bottom of the meniscus (curved surface) Bottom of Meniscus

24 Scientific Measurement: Mass: The amount of matter in an object. Basic Unit: Kilogram (1000 grams) Mass is usually measured using a triple beam balance. Note: Mass is not the same as weight.

25 Scientific Measurements: Density: The amount of mass in a given volume of an object. Density may be affected by: 1. Air trapped in the object. 2. Temperature of an object.

26 Scientific Measurements: Density = Mass per unit volume of a substance Calculated by: Density = mass divided by volume d= m V Water density 1 g/ml

27 Scientific Measurements: Q: If wood floats in water, is its density greater than or less than one?

28 Scientific Measurements: Temperature: The amount of heat in an object Basic Unit: Kelvin (K) Derived Unit: Celsius ( C) 0 C = Freezing point of water 100 C = Boiling Point of water Body Temp: 37 C Room Temp: 21 C Measured using a thermometer (usually alcohol)

29 Scientific Measurements: To convert temperatures: K = C C = K -273 F = 9/5( C + 32) C = 5/9( F 32)

30 Dimensional Analysis: Dimensional Analysis (DA): Method of converting one unit to another Uses a conversion factor- a factor that is always equal to one e.g grams 1 or 1kilogram 1 1 kilogram 1000grams

31 Dimensional Analysis: Convert 1350 grams to kilograms 1350 grams x 1 kilogram grams Cancel grams and multiply x 1 kilogram = 1350 kg =1.35kg

32 Lab Safety: Never do anything until you are instructed. Wear safety glasses in the lab when you: Use fire of any kind. Handle hot glass. Measure, mix or pour hot chemicals.