What is Missing
from the classical explanation on the previous page?
Implicitly the previous analysis assumes that the last link stops only
due to an impulsive reaction from the table. There is assumed to be no interaction
between the last link and the chain above. Hence the upper portion of chain falls freely
with acceleration g. Why
shouldn't there be any force between the last link and the chain above?
It is intuitive to assume that when last link collides with the ground it
also breaks away from the chain above with no interaction. But
that is just an
assumption. In principle there can be a force
N2 with which the last link pulls down
on the chain above it.
Can we make a chain which sucks itself
on to the table it falls on?
What can N2 do ?... if it exists
If it's positive (pulling): it can make the chain section that is in the
air fall faster than gravity!
In some sense the
chain is being sucked by the surface its falling onto.
This page was
updated on March 13, 2011