Re: [Phys-l] Collision of irregular bodies

[ludwik kowalski <kowalskil@mail.montclair.edu>]

On Aug 14, 2006, at 1:19 PM, John Denker wrote:

> . . . Has anybody done an  experiment  that shows the force is
> reproducibly perpendicular to the plane of contact? . . .

John's question made me think about a possible experiment, for example, 
using two pucks on an air table. A collision can be recorded by using a 
camcorder, and then analyzed on the frame-by-frame basis. A good 
question to ask (instead of telling students what to do) is "how should 
the data be used to learn about directions of action-reaction forces?"

Many camcorders allow the shutter speed to be 0.001 s. But would the 
time intervals between frames (1/30 s) be sufficiently short to measure 
the direction of dp/dt?

Ludwik Kowalski
Let the perfect not be the enemy of the good.