Closed System Energy Balances (gn-Qo)+(Wn-Wou）=△Fsystem change in the amount net amount of energy net amount of energy of energy contained transferred in across transferred out across within a system the system boundary by the system boundary during some time heat transfer during by work during the interval the time interval time interval △E=Q-W 1st law AE=E2-E,=△U+AKE+APE i.e.,the energy of a system (U+PE+KE)changes due to work =m(4,-4)+5m(c-c2)+mg(32-z) and heat transfers between the system and surroundings 上降文通大学 March 7,2019 3 SHANGHAI JIAO TONG UNIVERSITYMarch 7, 2019 3 Closed System Energy Balances i.e., the energy of a system (U+PE+KE) changes due to work and heat transfers between the system and surroundings 1 st law 2 1 2 2 2 1 2 1 2 1 KE PE 1 ( ) ( ) ( ) 2 E E E U m u u m c c mg z z               