20. 21. ds Starting from the definitions of temperature = and heat capacity C = following identities: a) C = Tds prove the ds b) du dT 1 CT2 c) For two systems, A and B in equilibrium at temperature T, the scale of energy fluctuations is KT k k + CA CB Use the result of problem 20 part (c) to estimate the size of energy fluctuations between two 1.0 kilogram solid copper blocks put in thermal contact and isolated from any external influence. The specific heat of copper is 385 J/(kg K). Comment on the size of your result.