"cjcampbell" wrote:
"An airplane on a runway sits on a conveyer belt that moves in the
opposite direction at exactly the speed that the airplane is moving
forward. Does the airplane take off?"

One critical detail is missing that makes in impossible to say "yes" or
"no":

Is the forward speed of the plane above the stall speed?

The plane could, after all, being moving forward at 10 mph. Nothing in the
problem statement above precludes that speed, or any other. HOWEVER, the
question on the web site asks "_Can_ the airplane take off?" The answer to
that one is, using the most common meaning of the word "can," essentially
"yes". What a difference substitution of one word makes!

;-)