Chapter 1 Measurement 第1章 測量

Chapter 1 Measurement 1-1 What is Physics? 1-2 Measuring Things 1-3 The International System of Units 1-4 Changing Units 1-5 Length 1-6 Time 1-7 Mass

1-1 What is Physics? Science and engineering are based on measurements and comparisons. Global Positioning System (GPS) 全球定位系統

1-2 Measuring Things We measure each physical quantity in its own units, by comparison with a standard. Base standards must be both accessible and invariable.

1-2 Measuring Things standard 標準 unit 單位 base quantity 基本量 derived quantity 導出量 base unit 基本單位 derived unit 導出單位

SI Base Quantities length 長度 mass 質量 time 時間 electric current 電流 thermodynamic temperature 熱力學溫度 amount of substance 物質量 luminous intensity 發光強度

1-3 The International System of Units SI (Système International) 國際單位制 metric system 公制 scientific notation 科學記號、科學記法 3.56  109 m 4.92  107 s

10進位倍數和分數符號 字首 符號 10的次方 名稱 yotta Y 1024 佑 deci d 10-1 分 zetta Z 1021 皆 centi c 10-2 釐 exa E 1018 艾(百萬兆) milli m 10-3 毫 peta P 1015 拍(千兆) micro µ 10-6 微 tera T 1012 兆 nano n 10-9 奈(毫微) giga G 109 吉(十億) pico p 10-12 皮(微微) mega M 106 百萬 femto f 10-15 飛(毫微微) kilo k 103 千 atto a 10-18 阿(微微微) hecto h 102 百 zepto z 10-21 介 deka(deca) da 101 十 yocto y 10-24 攸

1-4 Changing Units conversion factor 換算因子、換算因數 significant figure 有效數字 decimal place 小數位、小數位數

1-5 Length In 1792, Republic of France established a new system of weights and measures. The unit of length, the meter, was defined as one ten-millionth of the distance from the north pole to the equator. International Bureau of Weights and Measures 國際度量衡局 Standard meter bar Platinum-Iridium bar

1-5 Length In 1960, the meter was defined to be 1650763.73 wavelengths of a particular orange-red light emitted by krypton-86 in a gas discharge tube. Krypton 氪 Gas discharge tube 氣體放電管

1-5 Length In 1983, the meter was defined as the length of the path traveled by light in a vacuum during a time interval of 1/299 792 458 of a second. The speed of light c is then exactly c = 299792458 m/s.

Standard 標準 Base standards must be both accessible and invariable. primary standard 原級標準、原標準 secondary standard 次級標準、副標準 order of magnitude 數量級

1-6 Time Time has two aspects Earth’s rotation Quartz clock 石英鐘 When did it happen? What is its duration? Earth’s rotation Quartz clock 石英鐘 One second is the time taken by 91992631770 oscillations of the light emitted by a cesium-133 atom. Atomic clock 原子鐘 National Institute of Standards and Technology (NIST) 國家標準與技術研究院

10-hour watch

Variations in the length of the day over a 4-year period

1-7 Mass Carbon-12 atom atomic mass unit, u 原子質量單位 1 u = 1.66053886  1027 kg Density,  密度 liquefaction 液化 quicksand 流沙

The international 1 kg standard of mass (platinum-iridium)

Uncertainty 誤差 Accuracy 準確度 Precision 精密度、精確度 Accuracy refers to how close a measurement is to the true value. Precision 精密度、精確度 Precision in a strict sense refers to the repeatability of the measurement using a given instrument.