f(1)A process involving only infinitesimal ote. changes in the thermodynamic parameters of a system is known as an infinitesimal(无穷小的) process. For such a process, the fist law becomes do=dE +dw It represents the mathematical relation of transformation among the internal energy, heat and work. do and dw represents only a small amount of heat and work, having no differential meanings (f 分)
（ 1 ） A process involving only infinitesimal changes in the thermodynamic parameters of a system is known as an infinitesimal（无穷小的） process. For such a process, the fist law becomes dQ = dE + dW It represents the mathematical relation of transformation among the internal energy, heat and work. Note: and represents only a small amount of heat and work, having no differential meanings（微 分）. dQ dW
(2)There is not any system(machine) that can do work forever without the supply of heat(第一类永 动机是不可能的). =(E2-E1)+W Mouse 劳逸结合 Eat, Study, work and sleep
(2)There is not any system(machine) that can do work forever without the supply of heat(第一类永 动机是不可能的）. Q = (E2 − E1 )+W 劳逸结合
热力学第一定律指出: 第一类永动机是不可能实现的 第一类永动机: E2-E1=0(循环) Q=0 (外界不供给能量) W>0 (对外界作功)
热力学第一定律指出： 第一类永动机是不可能实现的。 第一类永动机： E2 - E1= 0 （循环） Q = 0 （外界不供给能量） W > 0 (对外界作功)
(3)“heat” is energy that a given system has absorbed from or released (A)) to its surroundings “work” is work that a given system has done on its surroundings or its surrounding have done on the system. Heat system y Work
（ 3 ） “ heat” is energy that a given system has absorbed from or released（释放） to its surroundings; “Work” is work that a given system has done on its surroundings or its surrounding have done on the system. Heat system Work
2.The work and heat of a process We do not intend to discuss the calculation of heat and work in a complicated process, and only deal with a equilibrium process of a gas such as an ideal gas as in shown in the following figure in which the expansion of gas in a piston(以活塞理想气体的膨胀 为例)。 dXI f= ps or eX
2.The work and heat of a process We do not intend to discuss the calculation of heat and work in a complicated process, and only deal with a equilibrium process of a gas such as an ideal gas as in shown in the following figure in which the expansion of gas in a piston（以活塞理想气体的膨胀 为例）。 f = pS dx or Fex