Re: [Phys-L] Nice question on buoyance and balance

[John Denker <jsd@av8n.com>]

On 01/29/2014 01:15 PM, Jeffrey Schnick wrote:
> Could you please spell out your complete momentum flow argument
> leading up to and including the statement that the right side goes
> down.

Start with the steel ball suspended above the water.  All the 
momentum is accounted for:  The crane supports the ball and the 
scale supports the beaker + water.

Now lower the ball into the water.  The crane now supports one
displacement-worth less weight.  By process of elimination, the
scale now supports one displacement-worth more.

The ping-pong ball is chump change.

What am I missing?  I could be missing something.  I solve these
things subconsciously, far removed from any attentive, sequential,
conscious process.  It's a bit like an archaeological dig to go 
back and try to figure out what happened.  It's hard to describe 
it in logical, sequential terms.


=================
For extra credit:

Note that the weight of the steel ball doesn't actually matter,
only the displacement.  Oddly enough, the displacement of the
ping-pong ball doesn't matter, only its weight.  As long as
the displacement of the steel ball exceeds the weight of the
ping-pong ball, the thing tilts.