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I am curious as to whether anyone can confirm the explanation given
in the Jan 2018 "Figuring Physics" solution provided in the Physics
Basically, the question is whether cooling would occur if molecules
of every speed in a liquid had an equal chance of escape from the
surface. The answer given in the column is no, with a rationale that
the cooling occurs because the faster ones are the ones that are
leaving and the slower ones are left behind.
The reason I ask is because I used to use somewhat similar logic but
I stopped for two reasons. First, the "slow molecules left behind"
implies that the remaining liquid becomes cooler than the vapor that
is produced. Second, I feel it obscures the fact that the process of
leaving (which is a sort of bond breaking) requires an extraction of
energy from the surroundings, regardless of whether the molecules
involved were initially going faster or slower.