Re: falling magnet demo

[Lowell Herr <herr@catseq.catlin.edu>]

Don,

I do this experiment and the magnet is in fact slowed.  Here are a few 
suggestions.  Make sure the magnet just fits in the copper pipe while 
still moving smoothly.  I have 
seen some teachers use two copper pipes if the wall is not sufficiently 
thick for the original pipe.  For the magnet, I use what is called a "cow 
magnet" as they are quite strong.   What are you using for a magnet?  My 
guess is, that is the problem.

Lowell Herr

Project PHYSLab
The Catlin Gabel School
Portland, OR 97225
On Mon, 10 Mar 1997, JFDWG wrote:

> I tried a classic demonstration of dropping a magnet through a copper
> tube at the same time as dropping an unmagnetized bar.  They both
> landed at the same time.
> Since one possible explanation was that the magnet's speed was not
> great enough, I set a pvc tube on top of the copper tube so that
> the magnet would have a significant speed when it reached the copper.
> Still, they both fell with normal acceleration.
> Can anyone explain why the magnet was not slowed when falling through
> the 50 cm long copper pipe?
> Thanks,
> Don Greenberg