I've been asked to find the final temperature of different in an insulated container. A combination of 0.25kg water at 20C, 0.4kg aluminum at 26C, and 0.1kg copper at 100C are combined, and allowed to come to thermal equilibrium. Finding the equilibrium temperature for two substances is easy enough, but throws me off when another one is involved... I approached the problem by finding the equilibrium temperature between aluminum and water separately (21.5 C), and copper and water (22.8 C). Q(Al) = Q(H2O) --> Tfinal = 21.53C Q(Cu) = Q(H2O) --> Tfinal = 22.85C My rationale is that both of the metals will heat the water separately, and then the water at two different temperatures will mix. But now that I have the final temperatures of each metal in equilibrium with water, I'm not quite sure how to proceed. I don't think I would just average the two values, as the amount of water heated by both metals is different.