Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: Name that force



On Tuesday, Oct 28, 2003, at 09:12 US/Pacific, John S. Denker wrote:

... Let me take this opportunity to chime in with another
word that could be used to "name that force" ...
hydrostatic pressure (in addition to the previously-
mentioned viscosity). If we make the steady-state
approximation, and a few other approximations, there
will be a pool of water on the bottom of the boxcar,
and the surface of the water will have a slope. The
steady addition of new water will, via viscosity etc.,
maintain this slope. The hydrostatic pressure will
push on all the walls, but because of the slope
there will will be greater force on the back wall,
resulting in deceleration.

The water surface would be horizontal at constant speed.
But in a slowing down car the steady slope will be negative
(assuming the car is moving in the positive x direction). The
magnitude of the slope is an indicator of acceleration. Yes,
in that sense the viscosity might "play a role."

Therefore I would expect more pressure on the front wall
and not on the back wall. What am I missing?
Ludwik Kowalski