HonG-KonG-PhysiCs-OlympiaD-2006-–-PrEliminary-ContEst二零零六年香港物理奥林匹克预选赛.doc

Hong Kong Physics Olympiad 2006 – Preliminary Contest二零零六年香港物理奧林匹克預選賽 Organized by Physics Club物理學會主辦 March 10th, 2006二零零六年三月十日 Rules of the Contest比賽規則 The competition comprises a 70-minute written test.比賽以筆試形式進行，為時70分鐘。 The full mark of this paper is 25.6.全卷滿分為25.6分。 There will be multiple-choice and open-ended questions in bilingual versions. Contestants must answer all questions. They can answer in either Chinese or English.試題分爲選擇題及開放式問答題，題目中英對照，參賽學生可選擇以中文或英文作答，但必須解答全卷所有題目。 Contestants should present the solutions clearly when solving open-ended questions.作答開放式問答題時，參賽學生須清楚交代解題步驟。 All answers should be either exact or corrected to three or more significant figures unless otherwise specified.除特別指明外，所有最終數值需完全準確或取三個或以上的有效數字。 Calculators that are HKEAA-approved can be used for the event. Measuring instruments like rulers, compasses, etc. can also be used.比賽時，學生可使用香港考試及評核局認可之計算器。直尺、圓規及其它量度工具亦可作輔助之用。 The following conditions will be applied unless otherwise specified: All objects are near Earth surface and the gravity is pointing downwards. Neglect air resistance. All speeds are much lower than the speed of light. 除特別指明外，本卷將使用下列條件： 所有物體都處於地球表面，重力向下。 忽略空氣阻力。 所有速度均遠低於光速。 Physical Constants and Formulae for Reference供參考之物理常數及公式 Acceleration due to gravity地心加速度g = 9.80665 m s-2. Atmospheric pressure大氣壓強p0 = 1.01325 × 105 Pa. Gas constant氣體常數R = 8.31447 J K-1 mol-1. Permittivity in free-space真空介電常數ε0 = 8.85419 × 10-12 C2 N-1 m Speed of light in vacuum真空光速c = 2.99792 × 108 m s Zero degrees Celsius攝氏零度0 °C = 273.15 K. Properties of water:水的性質: Specific heat capacity比熱容cw = 4.18 × 103 J kg-1 K-1 Latent heat of vaporization氣化潛熱Lv,w = 2.26 × 106 J kg-1 Density of steam水蒸氣密度ρs = 8.03 × 10-1 kg m Molar mass摩爾質量Mw = 1.80 ×10-2 kg Ideal gas law理想氣體方程 pV = nRTp: Pressure in gas氣體中的壓強V: Volume occupied by gas氣體佔的體積T: Temperature (in kelvins) of gas氣體的絕對溫度n: Number of moles of gas氣體的摩爾數 Coulomb force between two charges電荷間的庫倫力 F: Force experienced by