SOME HOT STUFF AND COOL THINGS
a Hotter Object?
The answer to the question is, of course, no: in contact between two objects, the heat goes from the hotter object to the colder one.1 So the following question may sound silly:
Problem. Can a glass of 100° C water heat a glass of 0° C milk to more than 50° C, their common temperature if mixed together? The glasses are of the same size. Let's also assume that water and milk are completely identical in all their thermal properties.2 No heat can be brought in from the outside, but additional containers can be used.
Solution. Such heat transfer is possible without violation of the second law. All we need is an extra empty glass and a small ladle. Scoop up a ladle of cold milk, dip it into hot water, and wait for the temperatures to become practically
1 This is a consequence of the second law of thermodynamics, an experimentally established fact.
2 In particular, they have equal specific heat capacities: equal amounts of heat give equal masses equal temperature increases.