1.Discuss whether it makes physical sense to say something is “twice as hot” as something else, either in an everyday sense of the words or a physics sense.

2.Two identical bubbles of gas form at the bottom of a lake, then rise to the surface, expanding as they rise (since the pressure is lower nearer the top of the lake). Bubble A rises very quickly, so no heat is exchanged with the water. Bubble B rises slowly, so that it always remains in thermal equilibrium with its surrounding water (which has the same temperature everywhere). Discuss which of the bubbles is larger by the time they hit the surface.