Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!mhuxj!houxm!vax135!cornell!uw-beaver!tektronix!hplabs!sri-unix!rsmith.pa@XEROX.ARPA
From: rsmith.pa@XEROX.ARPA
Newsgroups: net.physics
Subject: Re: Helium baloon in car
Message-ID: <12145@sri-arpa.UUCP>
Date: Tue, 18-Sep-84 12:32:48 EDT
Article-I.D.: sri-arpa.12145
Posted: Tue Sep 18 12:32:48 1984
Date-Received: Tue, 25-Sep-84 21:03:57 EDT
Lines: 23

Another way to understand why the helium baloon wants to go opposite to
fuzzy dice in a turning car:

Imagine watching the car turn left from above.

Imagine replacing the baloon for a moment with a blob of air of the same
shape.

What does that blob of air do? Nothing much - it swings to the left with
the rest of the car.

Obviously there are forces to the left that act on that blob-shaped
region - forces arising from the surrounding air that caused the air to
bend its path into a circular arc.

Replace the air blob with the helium baloon: the same forces are acting
on the blob shaped region. But the mass inside that region is less now!
Thus the resulting acceleration will be smaller, and the velocity vector
will be bent less. The baloon doesn't swing left quick enough to keep up
with the car.

Replacement with surrounding fluid blobs is a general way to think about
all problems involving helium baloon-type situations.