How is momentum conserved when a cue ball hits a nerf ball?

The vector sum, before and after, is identical. The vectors themselves
are different (kinetic energy is converted to heat and such) but looking
at both balls, or even looking at a cue ball and a glue ball, the center
of gravity moves with the same velocity before and after.

If the air has a net increase in downward momentum, how is
momentum conserved.

....by the air's eventual collision with the earth. Momentum is
similarly conserved when an object merely falls. The momentum gained by
the falling object is cancelled by the momentum acquired by the earth
rising up to meet it. In the case of "mysterious phantom gravity" not
associated with the earth, momentum is not conserved, it disappears into
the phantom gravity. This is one of the reasons why phantom gravity is
not experimentally supported.

If you ignore the earth, you are in the same position.

I don't deny that downflow occurs. The pont is that downflow is a
consequence of lift, not the cause of lift, and it is balanced by
upflow, (albeit a more diffuse flow) otherwise the upper atmosphere
would run out of air.

If there were no earth for the smooshed-together air to crowd up
against, the upper atmosphere =would= run out of air.

Jose
--
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