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

[Jeffrey Schnick <JSchnick@Anselm.Edu>]

> -----Original Message-----
> From: Phys-l [mailto:phys-l-bounces@phys-l.org] On Behalf Of John Denker
> Sent: Wednesday, January 29, 2014 4:35 PM
> To: Phys-L@Phys-L.org
> Subject: Re: [Phys-L] Nice question on buoyance and balance
>
> 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.
Despite the use of the word "momentum," I see nothing in this explanation that indicates that the author was thinking in terms of momentum flow rather than forces.