Why need the second law? First law-energy conservation (Quantity) dt How about the Quality of the energy? 中同人长第 4C61676666 C61676656 100 100 好好学习 上游究通大学 April 8,2018 2 SHANGHAI JIAO TONG UNIVERSITYApril 8, 2018 2 Why need the second law? First law – energy conservation How about the Quality of the energy? (Quantity)