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Unformatted text preview: CHAPTER 1 Physical quantities, measurements and units of measure 1. Physical quantities, standards and measurements Physics is the study of natural phenomena through the definition, characterization and experimentation of physical quantities . Physical quantities are characterized by: A number that describes the magnitude of the quantity. If the quantity is a vector, one needs a magnitude and a direction . A unit of measure , which describes the nature of the quantity. a method to perform the measurement of the physical quantity. Relationships among physical quantities constitute the laws of physics, and they are to be determined experimentally. Every law of physics is tentative, that is, it is true until a counter-experiment proves it wrong. At that point, the law is no longer valid. The primary physical quantities, or base quantities, are those that can be measured directly by comparison with a standard . Among the primary quantities are: Length, which expresses the distance or extent in space. The standard used for mea- surement is a standard stick kept at the International Bureau of Weights and Stan- dards near Paris, France. An object of the same length as the standard bar is said todards near Paris, France....
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This note was uploaded on 07/22/2011 for the course PH 111 taught by Professor Bonamente during the Fall '08 term at University of Alabama - Huntsville.
- Fall '08