Goofball_star_dot_etal wrote:

/snip/
No work is done on a plane in level fight at constant speed. Its
potential energy is not increasing with height and its kinetic energy is
not increasing with velocity. The lift is equal to its weight and its
drag is equal to the thrust. All the power ends up heating the air,
although initially some goes into increasing the kinetic energy of the
air you cannot get at this number by looking at the lift, as you
suggest, since kinetic energy and momentum are not the same thing.


Hmmmm. a mostly reasonable review - but the idea that force times
distance is not equal to work is somewhat radical, don't you think?

And if the force (usually called thrust in this context,)which was
provided to oppose the drag on the plane due to its airspeed, is
multiplied with the airspeed rather than some air distance - the work
becomes the power expended in opposing drag.

But you knew that, I'm sure - you were just trying to provide a gut feel
for the physics, huh? :-)

Brian W