A 25.8 g block of copper whose temperature is 406 K is placed in an insulating box with a 53.4 g block of lead whose temperature is 213 K.
(a) What is the equilibrium temperature of the two-block system, in kelvins?
(b) What is the change in the internal energy of the two-block system between the initial state and the equilibrium state?
(c) What is the change in the entropy of the two-block system? The heat capacities of copper and lead are 386 J/kg·K and 128 J/kg·K, respectively.