From: Andrew Coblentz (acsl@mindspring.com)
Date: Fri Jun 06 2003 - 17:19:58 PDT
Message-ID: <002701c32c8a$8842e420$bb29fea9@oemcomputer> From: "Andrew Coblentz" <acsl@mindspring.com> Subject: Re: pinhole Re: Golf Ball Date: Fri, 6 Jun 2003 17:19:58 -0700
Good question. The sidewalk was certainly rougher than a concrete basement
floor or a linoleum floor. Your explanation is right on point.
----- Original Message -----
From: ROY MAYEDA <roymayeda@yahoo.com>
To: Pinhole <pinhole@exploratorium.edu>
Sent: Friday, June 06, 2003 7:36 AM
Subject: pinhole Re: Golf Ball
> Andrew,
>
> It just occurred to me as I was bouncing a golf ball
> this morning, anticipating our end-of-year golf
> outing, that I think I missed something. Was there
> some TEXTURE to the sidewalk you were on? Each time I
> checked (at home on the concrete basement floor and
> just now at school on linoleum) the surface was very
> flat and smooth. If there are irregularities (like in
> rough asphalt or concrete pavement), striking one of
> these surface irregularities unevenly would impart
> spin to the ball. (Just like if you drop it on an
> incline, the ball will roll down the hill.) If the
> center of mass is not above the support (contact)
> point, the ball will begin rotating in the direction
> that the CM is is shifted from the support point.
> This would also explain why the rotation may speed up,
> stop, or reverse on subsequent bounces, depending on
> the orientation (distance and direction) of the CM and
> support point. A little late, but better late than
> never.
>
> Roy Mayeda
> Sauk Centre HS (last day)
> Sauk Centre, MN
> (may be working in SD next year -- it's 60 miles
> closer!)
>
> Original Message
> From: "Andrew Coblentz" <acsl@mindspring.com>
> Subject: Golf Ball
> Date: Sun, 9 Mar 2003 18:22:38 -0800
>
> I found a golf ball on the street. As I bounced the
> golf ball, I noticed that it hardly spun as I dropped
> it, but spun rapidly after it rebounded off the
> sidewalk. What is the explanation for the increased
> spinning?
>
>
>
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