Two conveyor belt scenarios

Actually, on a moving river, water speed matters and frequently speed
(well, distance really) relative to the ground matters. The ideal setup
is to have a headwind while pointing downstream. That way you have
slowest waterspeed and shortest run. BUT....local obstructions dictate
you concern yourself with distance of run relative to the land....

Like I said, it can get complicated.

Gary Drescher wrote:
"Doug" wrote in message
oups.com...
There are three speeds here. Speed relative to the air. Speed relative
to the belt. Speed relative to ground.

The only velocities that matter are that of the plane relative to the air,
and that of the air relative to the landing surface (in this case, the
constant-speed conveyor belt). The landing surface's velocity relative to
the surrounding ground has no physical effect on the landing (except perhaps
with respect to turbulence, but that's not part of the hypothetical
scenario).

And actually, this does have a real world analogy. Taking off in a
seaplane on a river that is moving. Now add in wind blowing upstream or
wind blowing downstream and the takeoff and landing upstream vs
downstream comparison gets quite complicated.

If the river is arbitrarily long (as we're assuming the conveyor belt to be)
and you don't care where on it you end up, then the landing isn't
complicated at all: you just ignore the land completely, and pay attention
to the wind speed relative to the water. (It helps to have a wind sock
that's riding on the river or on the conveyor belt.)

--Gary