From: utzoo!dciem!mmt
Newsgroups: net.physics
Title: Re: strategy in rainstorms - (nf)
Article-I.D.: dciem.161
Posted: Fri Jan 28 14:48:16 1983
Received: Fri Jan 28 16:59:14 1983
References: watarts.1646

You can imagine your body sweeping out a volume of space in the rainstorm.
If you stay in the rain for a time T, you will sweep out ATv cubic whatevers
(A is the area you present to the rain, v the velocity you have relative
to the rain) and all the rain in this volume will hit you.
If you stay in the rain for a fixed time, it is best to stand still,
or at least move at the speed of the wind, so that v is only the
vertical velocity of the rain and A consists of your head and shoulders.
If you need to go a certain distance, and do it very fast, Tv is
essentially independent of your running speed, since v is dominated
by your speed. But as your speed increases, so does A, the area you present
to the rain (unless you lean very far forward, so that you still
present your head and shoulders to the rain -- ie lean exactly as much
as the perceived slant of the rain). At intermediate speeds, v includes
components from both your velocity and that of the rain. Best to take
an umbrella. I haven't worked it out, but there may be an optimum
running rate for any particular trip in the rain. Maybe fastest is best
if you can do it on your stomach.
		Martin Taylor