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The Methods of Scientists

The Methods of Scientists. Section 1.2. Objectives. Compare and contrast independent and dependent variables. Compare and contrast experimentation and investigation. Identify the differences between mass and weight. Explain what scientific notation is and how it is used. Vocabulary.

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The Methods of Scientists

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  1. The Methods of Scientists Section 1.2

  2. Objectives • Compare and contrast independent and dependent variables. • Compare and contrast experimentation and investigation. • Identify the differences between mass and weight. • Explain what scientific notation is and how it is used.

  3. Vocabulary • scientific methods • hypothesis • experiment • independent variable • dependent variable • control • Le Système International d’Unités (SI) • scientific notation

  4. The Scientific Method • All scientists follow similar steps to investigate different areas of science. These steps must address the following items: • Must use a specific method/steps to follow • Must be recorded • Must be repeatable and yield the same results • By the scientist who originally did the work • By other scientists • Must be communicated to other scientists

  5. The Scientific Method • The Scientific Method is a series of problem solving steps that all scientists use to conduct experiments. • Although we are going to define steps for the method, it is not a rigid approach. • Variation is allowed.

  6. The Scientific Method • Scientific methods are used by scientists to help organize and plan their experiments and investigations.

  7. The Nature of Scientific Investigations • Experimentation: • An experiment is classified as an organized procedure that involves making observations and measurements to test a hypothesis. • Hypothesis • a testable explanation of a situation that can be supported or disproved by careful procedures. • Variables • The independent variable in an experiment is the factor that is changed by the experimenter. • A dependent variable is a factor that is affected by changes in the independent variable. • Controls • A control is used in an experiment to show that the results of an experiment are a result of the condition being tested.

  8. The Nature of Scientific Investigations • Investigations • An investigation involves observation and collecting data. • Analysis and Conclusions • During a scientific experiment, all data are carefully recorded. • Once an experiment is complete, graphs, tables, and charts are commonly used to display data. • These data are then analyzed so that a conclusion can be drawn.\ • You must summarize your results and what they mean in a written conclusion.

  9. The Nature of Scientific Investigations • Analysis and Conclusions (cont.) • Many times, a conclusion does not support the original hypothesis. • In such a case, the hypothesis must be reevaluated and further research must be conducted.

  10. The Scientific Method

  11. Steps of the Scientific Method • Observe/Gather Background Information on an Unexplained Phenomenon. • Make a Hypothesis • A hypothesis is a statement about the phenomenon you have observed. • This statement must be testable. • You then test your hypothesis (conduct an experiment) • Compare your results to your hypothesis. • Draw a conclusion. Do your results support your hypothesis? • Revise your hypothesis as necessary – retest. • Repeat revise/retest/conclude as many times as necessary until hypothesis is supported. • Repeat experiment additional times to verify the hypothesis is corret. • Report your results to other scientist – allow them to verify your work. • Your work is accepted!

  12. A Phenomenon – What do you observe?

  13. What is your hypothesis?

  14. How do you test your hypothesis?

  15. Analysis/Conclusion

  16. The SI System • Le Système International d’Unités (SI) is a modern version of the metric system based on a decimal system. • In 1960, the SI System was a revision of the meter/kilogram/second version of the Metric System. • The system has been nearly globally adopted. Three principal exceptions are Burma (Myanmar), Liberia, and the United States. • The United Kingdom has officially adopted the International System of Units but not with the intention of replacing customary measures entirely.

  17. The SI System • Length • The SI unit for length is the meter (m). • Mass • The amount of matter in an object is called mass. • The SI unit of mass is the kilogram (kg). • Weight • Weight is a measure of the gravitational force on an object. • The SI unit for force is the newton (N). • Time • Time is the interval between two events. • The SI unit for time is the second (s). • Temperature • Temperature is a measure of the average kinetic energy of the particles that make up a material. • The SI unit for temperature is the kelvin (K). • Absolute zero is the coldest possible temperature.

  18. The SI System Base Units

  19. Kelvin Temperature Although Kelvin is the SI unit, in practice we will use the Celsius Scale

  20. Derived Units • Area • Area is the amount of surface included within a set of boundaries. • The SI unit for area is square meters (m2). • Volume • Volume is the amount of space occupied by an object. • The SI unit for volume is cubic meters (m3). • Density • Density is the measure of the amount of matter that occupies a given space. • The SI units for density areexpressed in grams per cubic centimeter (g/cm3), grams per milliliter (g/mL), and kilograms per cubic meter (kg/m3).

  21. Derived Units • Other units in the SI are derived (made) by combining units:

  22. Larger/Smaller Units • The SI system uses prefixes on the base units to make the unit larger or smaller:

  23. Practice What unit would you use to: • measure the distance from your house to the school? • determine your mass? • measure the length of 5th Block? • if you were preparing a weather report? • measure the mass of a paper clip?

  24. Practice (cont.) What unit would you use if you were: • measuring the thickness of your pencil/pen? • measuring the mass of a penny? • writing a density? • measuring the volume of this room? • measuring the area of the football field?

  25. Scientific Notation • In scientific notation, a number is expressed as a value between 1 and 10 multiplied by a power of 10. • Form is M x 10N • M must be > 1 and < 10 • N is an integer • Examples • The number of grains of sand on Earth is approximately 4,000,000,000,000,000,000,000 and would be written as 4  1021. • The mass of Earth at 5,974,200,000,000,000,000,000,000 kg would be written as 5.9742  1024 kg.

  26. Practice • The age of the Earth is approximately 3.5 billion years. If 1 billion = 1,000,000,000, what is the age of the Earth in scientific notation? • Pluto is approximately of 5,913,000,000 km from the Sun. Write this number in scientific notation. • However, should Pluto ever be near its closest point to Earth's orbit when the Earth is also near that point, the closest approach between the two would be 4.3 x 109 kilometers. Write this value as a non-scientific notation number.

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