"Tony" wrote in message
oups.com...
Exactly right.

In the end we'd have to say it's a nicely phrased question. My first
instinct was to say the ariplane had zero speed relative to the ground
the moving belt is on, but that is NOT the condition the problem
stated.

So, under the usual circumstances (not having a significant tail wind,
for example) you'd lift off assuming the wheels are not going to self
distruct turning at twice their usual takeoff speed.

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).

--Gary