Re: Energy, etc

[Jim Green <JMGreen@SISNA.COM>]

> Jim Green notes "One does not have to go that far: There _is_ an
> effective force on the CM.
> The wall pushes on the finger bones; the finger bones push on the
> wrist
> bones; the wrist bones push on the ulna, the ulna pushes on the
> humerus,
> the ... "
>
> All true, Jim, but irrelevant to the question of whether or not an
> external force is doing work on the person and thereby causing a
> change in kinetic energy.

Not irrelevant! The person moves!  The hand does not move and no work is
done on the hand.  But the elbow moves so work is done on the elbow -- by
the ulna ... etc  -- at some point work is done on the CM bone and the
person moves.

Yes AND the Earth moves and work is done on the Earth!!!  AND therefore
work is done on the person by the Earth!!!!!

IE The wall moves!

The ankle bone is connected to the leg bone, the leg bone ....



Jim Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen