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.