(2310-4.1) Energy Balance （原曲：林家謙-下一位前度）（2019） V1: Net Energy transfer Equals to all delta E In piston, PdV, Area under process curve's W Both PV's difference over 1 minus n, polytropic P delta V, constant P And PV log ratio of Vs isothermal V2: Q minus W, delta U, cause no KE or PE here P delta V is W b, Q minus that, W other, it's delta U This Equals to delta H, m(h2 minus h1) Since the pressure is constant, there is nothing wrong It's used for constant pressure expansion contraction C: Remember E in minus E out Equals to delta E of system Delta U plus boundary work is delta H Enthalpy is U plus PV It's just Q minus W other Used in closed system under constant pressure V3: Stationary zero KE PE change process Insulated negligible heat transfer, E's zero, no work interactions Then you form equation, it's just so straightforward Then you can visualize it on PV diagram Find quantity with pure substance properties or ideal gas law (Repeat C) B: Find your P V T all by the tables Find x in final state, judge it and find T Then u is just u f times x u fg If ideal gas, make sure you have V and P Then you have drawn your PV diagram You just take area, or use the right process formula (Repeat C) （本人寫於2022年10月，這首歌幫我拿到A range）
