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Re: Name that force



This is still a totally inelastic collision: the initial horizontal speeds
were already equal, but energy must be dissipated to equalize the vertical
speeds. The car maintains a constant (horizontal velocity). The kinetic
energy dissipated is only that which was associated with the initial
VERTICAL motion of the water.
P.S. Do it in the rest frame of the car to see a totally inelastic VERTICAL
interaction.

-Bob Sciamanda

----- Original Message -----
From: "Ludwik Kowalski" <kowalskil@MAIL.MONTCLAIR.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Tuesday, October 28, 2003 1:40 PM
Subject: Re: Name that force


On Tuesday, Oct 28, 2003, at 06:37 US/Pacific, Chuck Britton wrote:

The force is the impact of each raindrop that hits the BACK wall of
the car or the FRONT of the FRONT wall of the car.

Relative velocity of the drops is slanted backwards, from the car's
point of view.

That is an important observation. The situation
can be further idealized. A cloud producing rain
is replaced be a shower-head staying above the
car. In that way the BACK wall and the FRONT
wall are dry. Will the car still be slowing down at
a rate proportional to the rate at which the mass
is increasing? I do not think so.
Ludwik Kowalski