01Chap1Introduction教程.pptVIP

* Introduction Chapter 1 * Getting prepared!!! Chapter 1. Introduction Measurement, Models, Theories and Laws Vector and Scalar 1-1 Models, theories, and laws (P3) Model: is a kind of mental image of the phenomena in terms of something are familiar with. Theory: is broader, more detailed, and attempts to solve a set of phenomena. Law: are general statements about how nature behaves. The statement takes the form of a relationship or equation (方程) between quantities (量). 1-2 Measurement and Uncertainty; Significant Figures(P3-5) Physics is based on measurement of physical quantities (物理量). P3 Significant Figures(有效数字): The number of reliably known digits in a number is called the number of significant figures. P4 Mass of the Earth: 5,980,000,000,000,000,000,000,000kg or 5.98x1024kg Diameter of proton（质子）: 0.000000000000001m or 10-15m (or 1 E-15 on computers) The advantage is that it allows the number of significant figures to be clearly expressed. Scientific notation (科学记数法(p4) Write numbers in “powers of ten”. 1-4 Units, Standards, and the SI System (P5-7) Unit (单位): We measure each physical quantity in its own units(单位) by comparison with a standard. P5 SI System (国际单位制): There are so many physical quantities that it is a problem to organize them. Fortunately, they are not all independent （独立）. P7 In 1971, the 14th General Conference on Weights and Measures, The SI (International System) was adopted. It is based on meter, second and kilogram. It is also called Metric System (公制） or MKS system. Many SI (System International) derived units are defined in terms of these base units, such as: 1 watt = 1 W = 1 kg ·m2 / s3 The second metric system is CGS(P7), in which the centimeter, gram, and second are the standard units of length, mass and time. exa E 1018 peta P 1015 tera T 1012 giga G 109 Mega M 106 kilo k 103 Hecto h 102 deka da 101 deci d 10-1 centi c 10-2 mil