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## Ch. 1 Sec. 2

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**Ch. 1 Sec. 2**Methods of Scientists**1. Which objects in this photograph are used for**measuring? 2. For what kind of measurement is each object used?**Review Vocabulary**experiment: procedure performed in a controlled setting to test a hypothesis and collect precise data**A. Scientific methods -**A series of problem solving procedures that help scientists conduct experiments.**B. Hypothesis -**A testable explanation of a situation that can be supported or disproved by careful procedures**1. independent variable -**the factor that is manipulated by the experimenter a. Only one factor (or variable) should be changed during an experiment**2. dependent variable –factor that is affected by**changes in the independent variable**3. control - standard for comparison in an experiment**a. Shows results are a condition of variable being tested b. Only one thing changed**D. Investigation**1. Observing & Collecting Data 2. Safety**E. Analysis & Conclusion**Examine results – did they support your hypothesis? Avoid bias or prejudice – do not influence in a particular, typically unfair, direction**II. Measurement:**Le Système International d’Unités (SI) is a modern version of the metric system based on a decimal system**A.Length -**1. The SI unit for length is the meter (m). 2. 1 meter = 39.3700787 inches**B. Mass**1. The amount of matter in an object is called mass. 2. The SI unit of mass is the kilogram (kg). 3. 1 kilogram = 2.20462262 pounds**C. Weight**1. Weight is a measure of the gravitational force on an object. 2. The SI unit for force is the newton (N). 3. 1 newton = 0.224808943 pounds force**D. Area**1. Area is the amount of surface included within a set of boundaries. 2. The SI unit for area is square meters (m2).**E. Volume**1. Volume is the amount of space occupied by an object. 2. The SI unit for volume is cubic meters (m3).**F. Density**1. Density is the measure of the amount of matter that occupies a given space. 2. 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).**G. Time**1. Time is the interval between two events. 2. The SI unit for time is the second (s).**1. Temperature is a measure of the average kinetic energy**of the particles that make up a material. 2. The SI unit for temperature is the kelvin (K). 3. Absolute zero is the coldest possible temperature. H. Temperature**III. Scientific Notation**In scientific notation, a number is expressed as a value between 1 and 10 multiplied by a power of 10.**Example**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.**Example**The mass of Earth at 5,974,200,000,000,000,000,000,000 kg would be written as 5.9742 1024 kg.**1**The Nature of Science Why is scientific notation sometimes used when doing science? Answer: It is sometimes necessary when doing science to use numbers that are very large or very small. These numbers can be conveniently expressed by using scientific notation.**1**The Nature of Science Section 1.2 Vocabulary scientific methods hypothesis independent variable dependent variable control Le Système International d’Unités (SI) scientific notation