7 a scientific law a is a hypothesis b is the result

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7. A scientific law (a) is a hypothesis. (b) is the result of a theory that has been tested once or twice. (c) is the same as a concept. (d) must consistently describe a regularity in nature.
Lesson#2: Units and Measurements Learning Goals: 1. Distinguish between fundamental and derived quantities. 2. State the standard units and prefixes within the SI (or metric) system. 3. Convert numbers to the scientific notation format. 4. Define significant figures (SF) in measurements versus exact numbers. 5. Express measurements to the correct number of decimal places based upon the measuring instrument used. When you can measure what you are speaking about and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers your knowledge is of a meager and unsatisfactory kind Lord Kelvin ( 1824 – 1907 ) A. Fundamental Measurable Entities Scientists (all of us) are constantly making measurements. Some measurable entities such as length, mass, and time can be quantified simply by making one measurement . Others, like velocity, work, and force, require two or more measurements. Entities requiring one measurement are listed in the table. B. Standard Units Over the centuries people has attempted to standardize common units such as a unit of length, so that it means the same all over the world. Two systems have developed over the years and have persisted to this day. The International System (SI), or metric system, and the British system. The metric system (SI) has been the accepted international measurement system since about 1900. In this course we will use the metric system primarily. The table below lists the fundamental base units in the two systems of measure. Standard Units: Fundamental Unit a. Length b. Mass c. Time d. Temperature e. Amount f. Illumination g. Current flow
SI (Metric) English Length Meter Foot Mass Kilogram Pound-mass Time Second Second Temperature Celcius Fahrenheit Amount Kg-mole lb-mass mole Illumination candela Current ampere Metric units are nicely related by powers of ten. Consequently shifting from one size metric unit to another merely involves moving the decimal point appropriately. See table below. Metric Prefixes: Numerical value Prefix 1000000 meters (or 10 6 meters) = 1 megameter 1000 meters (or 10 3 meters) = 1 kilometer 0.1 meter (or 10 -1 meters) = 1 decimeter 0.01 meter (or 10 -2 meters) = 1 centimeter 0.001 meter (or 10 -3 meters) = 1 millimeter 0.000001 meter (or 10 -6 meters) = 1 micrometer 0.000000001 meter (or 10 -9 meters) = 1 nanometer The figure below demonstrates how prefixes are used within the SI system to represent larger or smaller amount by factor of 10. The prefix “deci” means “one-tenth of”. One meter length is equal to 10 decimeters. One decimeter length is equal to 10 centimeters. One centimeter length is equal to 10 millimeters. So all prefixes within the SI system are related by multiples of 10.

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