I’ve spent all day either teaching or writing draft grant applications and am consequently a bit knackered, so in lieu of one of my usual rambling dissertations here is another example from the file marked Cute Physics Problems, this time from thermodynamics. It’s quite straightforward. Or is it? Most people I’ve asked this question in private have got it wrong, so let’s see if the blogosphere is smarter:

Three identical bodies of constant heat capacity are at temperatures of 300, 300 and 100 K. If no work is done on the system and no heat transferred to it from outside, what is the highest temperature to which any one of the bodies can be raised by the operation of heat engine(s)?