# Cold

The first thing I’ve learned about cold today is that it doesn’t exist — it is just the absence of heat. Also, it has to do with kinetic energy and the velocity of molecules, or as Derb might put it, “Kinetic energy = .5(mass)(velocity)^2.” Thanks for all the emails. Here is a quick sampling:

YEAH, RIGHT

E-mail

Subject: A stupid question

The Frost Elf

WHY WE FEEL COLD I

E-mail:

Subject: Heat

Bona fides: MS in Mech Engr Rice University, worked for 2 years in

heat tracing industry (heat pipes in refineries and chemical plants),

NASA research engineer 3 years.

Don’t think in terms of cold, think in terms of heat and a lack of

heat. Heat is a form or energy, and it actually makes molecules expand

or spread apart, because they become more “energetic.”

Heat flows downhill – from a hot object to a cold object. In Iowa, or

in NH, the air lacks heat, and you produce heat. The cold you feel is

the heat energy leaving your body to flow “downhill” to the cold

outside.

WHY WE FEEL COLD II

E-mail:

Subject: What is cold

Temperature is related to molecules whizzing about and banging into each other. As it gets colder, the molecules slow down like traffic near the mall at Christmastime.

Density is the spatial distribution of molecules – how far apart they are. The heat your feel is due to the number and speed of the molecule whacking into you.

NO WAY!

E-mail:

Subject: A Scientifical Explanation of Cold Air

Actually, Timmy, mass becomes denser when it cools, so the molecules would come closer together when the temperature drops. When molecules cool, the kinetic energy drops, and thus the molecules vibrate slower. At absolute zero (the complete absence of heat) the molecules would lose all energy and would fall right to the floor and you’d trip on them. It’s true! Tell any scientist that at your local sciencetorium and he’ll think you’re smart.