课程名称︰普通物理甲上 课程性质︰系上必修 课程教师︰高涌泉 开课学院：理学院 开课系所︰物理系 考试日期（年月日）︰09.01.15 考试时限（分钟）：110min 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 1. A clock moves along an axis at speed of 0.6 c and reads zero as it passes the origin. What time does the clock read as it passes x = 180 m ? 10% 2. An observer in frame S detects 2 flashes of light. A big flash occurs at x1 = 1200 m and, 5*10^-6s latter, a small flash occurs at x2 = 480 m. For an observer in frame S', the 2 flashes occurs at a single coordinate x'. What is the time interval between the flashes for an observer in S'? 10% 3. A particle with mass m accelerated by a constant force F will, according to Newtonian mechanics, continue to acclerate without bound. That is, t→∞,v→∞. Show that according to relativistic mechanics, the particle's speed approaches c as t→∞. 20% 4. In the red shift of radiation from a distant galaxy, a certain radiation, known to have a waelength of λ1 when observed in the laboratory, has a wavelength of λ2(>λ1). What is the radial speed of the galaxy relative to Earth? 10% 5. An ideal diatomic gas, with rotation but no oscillaton, undergoes an adiabatic expansion. Its initial pressure and volume are Pi and Vi. Its final pressure is Pf. How much work is done by the gas? 10% 6. Consider a gas of molar mass M at temperature T. What is the fraction of molecules with speeds in the interval dv centered on speed v? 10% 7. In the 1st stage of a 2-stage Carnot engine, energy is absorbed as heat Q, at temperature T1, work W1 is done, and energy is expelled as heat Q2 at a lower temperature T2. The 2nd stage absorbes that energy as heat Q2, does work W2 and expels energy as heat Q3 at a still lower temperature T3. What is the efficiency of the 2-stage Carnot engine? 15% 8. What is the entropy change for n mol of an ideal monatomic gas undergoes a reversible increase in temperature from Ti to Tf at constant volume? 15% --

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