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Re: Name that force



On Monday, November 3, 2003, at 12:57 PM, Kari Uolevi Eloranta wrote:

kowalskil@mail.montclair.edu wrote:

Consider two kinds of "rain," one in which droplets
are made of water and another in which droplets
are made of honey. The rate at which the mass in
the car increases (uniformly over the entire surface)
is the same. Do you expect the rates of slowing down
be different for these two rains?
Ludwik Kowalski

On Tuesday, Oct 28, 2003, at 06:50 US/Pacific, Kari Uolevi Eloranta
wrote:

I think the viscosity of water plays a role in acceleration, also.
So,
for the total effect, you have to consider both the viscosity and
interactions with
the walls.

Terveisin, Kari Eloranta, Finland


britton@ncssm.edu 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. . . .

Well, to be honest, yes I would. If I consider a single droplet, it
takes time
to accelerate it in horizontal direction. Honey is stickier, so greater
force
is excerted on a honey droplet than on a water droplet thus causing
greater
acceleration.

Could you please explain to me what is wrong in my reasoning. Probably
I am just missing here something obvious, but I just cannot see it.

Best regards, Kari Eloranta

The question was: "Do you expect the rates of slowing
down be different for these two rains?" Kari's answer is:
"yes I would." And then Kari adds: "Final situation remains
the same in both cases (honey, water), but processess
are different in their rates."

In other words, each rain (water or honey) will eventually
bring the car to rest but the rates of slowing down should
be different. Do I understand you correctly, Kari? Which
car will stop first, according to you: one receiving water
or one receiving honey? The rates of accumulation of
the liquid are identical. This answer will help us to deal
with what might or might not "be wrong" in the reasoning.
Ludwik Kowalski