Here's an interesting question that came to my mind today:

Suppose I have two containers of water. I heat Container $A$ to $60°C$ and Container $B$ is chilled to $-20°C$. If I leave them both in rooms, which container of water will reach $20°C$ first (room temperature)? Assume every variable is controlled except the temperature of the water.

Container $A$ and Container $B$ are both $40°C$ from room temperature. Clearly Container $A$ needs to lose some thermal energy while Container $B$ needs to gain some. In both situations the water wants to reach thermal equilibrium at $20°C$, but which container will do it faster?

  • $\begingroup$ and does container $B$ remain in the liquid state? $\endgroup$ – Tofi Feb 19 '18 at 11:40
  • $\begingroup$ Actually the title and the body are totally unrelated. It is still possible to guess what are you asking for and as such you got answers and an important comment. $\endgroup$ – Alchimista Feb 19 '18 at 12:02
  • $\begingroup$ Yes, assume both stay in the liquid state (perhaps water wasn't the best example). $\endgroup$ – Landuros Feb 19 '18 at 12:06
  • $\begingroup$ I still suggest that you change the title as" for a body or a system is faster to heat or to cool" , something like that. $\endgroup$ – Alchimista Feb 19 '18 at 12:40

That depends on thermal capacity of the containers and thermal coductivity between the containers and the room. If the containers are exactly the same in these respects they will reach room temperature together.

  • 1
    $\begingroup$ If conduction is the dominant form of heat transfer. This isn't the case if radiative heat transfer is significant. $\endgroup$ – Chris Feb 19 '18 at 10:56
  • $\begingroup$ @Chris It's 2 containers of waters at less than 100°C, it's safe to assume that conduction is dominant. $\endgroup$ – Strata771 Feb 19 '18 at 12:49

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