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Re: air resistance

Date: Thu, 20 Nov 1997 08:26:54 -0500
From: "Richard W. Tarara" <rtarara@saintmarys.edu>
Subject: Re: help with air friction?

I have good success with foam balls (3.5 cm radius, about 3 grams in mass)
that you can buy from Oriental Trading for about $3/dozen. These reach
terminal velocity after only a couple meters fall. We time a variety of
falls of the range 20 cm to over 10 meters (our library provides the long
drops). The short drops are timed (with some difficulty) with photo-gates,
while everything over about 1 meter can be hand timed.
.........
For n = 2 they get really very good fits.

Another variant would be to use a camcorder. First v-term for the foam
boal alone, then for the same boal with a small nail in it, then with two
nails, etc. A good lab activity; can be linked with the error analysis.
I may try this next year. What is the highest terminal velocity when the
available space is h=10 meters, Richard? I was surprised by the nearly
pure v^2 relation at small v?
Ludwik Kowalski