The work done by or system is equal to ex dw= fax= PSax= pav for an infinitesimally equilibrium process
The work done by system is equal to dW = fdx = PSdx = PdV for an infinitesimally equilibrium process. f = pS dx or Fex
The total work during the process is obtained by integration (积分)of (2,P2) w=dw= pdv which is equal to the total area under the process curve connecting the initial state and final state. Therefore, work depends on the path of process
= = 2 1 d d V V W W P V which is equal to the total area under the process curve connecting the initial state and final state. Therefore, work depends on the path of process. P V ( , ) V1 P1 ( , ) V2 P2 The total work during the process is obtained by integration (积分） of
结论 体积功与路径有关,是一过程量,其值等于 PV曲线与V轴包围的面积
结论： 体积功与路径有关，是一过程量，其值等于 P-V曲线与V轴包围的面积。 P V ( , ) V1 P1 ( , ) V2 P2
We can rewrite the first law as Q=(E2-E1)+,PdV(73) Hence, heat depends on the path of process. 内能E是状态量,只与 始、末态有关,Q、W是过 程量,与过程进行的方式 (1,B) 有关。 2912 功和热只有联系到某一具体 的过程才能计算出它们来, 系统在某一状态时,我们不 能说它有多少热和多少功
内能 E 是状态量，只与 始、末态有关，Q、W是过 程量 ，与过程进行的方式 有关。 We can rewrite the first law as = − + 2 1 2 1 d V V Q (E E ) P V (7-3) Hence, heat depends on the path of process. 功和热只有联系到某一具体 的过程才能计算出它们来， 系统在某一状态时，我们不 能说它有多少热和多少功。 P V ( , ) V1 P1 ( , ) V2 P2
87-3 Application of the First Law to isochoric, isobaric& isothermal Processes理想气体 的等容、等压和等温过程 High temperature Water Boilet Intake valve Exhaust valve Condenser (a)Reciprocating type
§7-3 Application of the First Law to isochoric, isobaric & isothermal Processes理想气体 的等容、等压和等温过程