"Kpi$LyLcEhRo" wrote in message
oups.com...

Gary Drescher wrote:
The plane would take off from the treadmill even if there were a tail
wind
equal to Vr (though in that case, the wheels would be turning at *four*
times their usual speed).

in the case of a tailwind equal to Vlof, when the plane leaves
the ground, the wheels would spin at a speed 3 times their usual speed
and not 4.

Suppose the plane lifts of at an airspeed of 30 knots, and suppose a 30 knot
tailwind. At takeoff, the plane then has a 60 knot ground speed. By
stipulation, the treadmill moves backward as fast as the plane moves
forward, hence at 60 knots too. Thus, the wheels are turning at 120
knots--four times the usual speed.

Actually this entire question and solution is about adding
and substracting velocity vectors and a perfect example of Einstein's
relativity theory.

No, this is strictly Galilean relativity (from four centuries ago);
Einstein's relativity has no bearing on this discussion.

--Gary