Kinetic energy increase in a plane

QUESTION: You watch your friend take off in a jet plane, and comment on the kinetic energy she has acquired.
But she says she has no such increase in kinetic energy. Who is correct?

Answer:

There is no doubt that she has increased her kinetic energy. As you know energy is always conserved and the fuel burned by the plane as it takes off is converted to heat, sound, light, gravitational potential energy and the kinetic energy of the plane and its passengers.

I suppose your fiend is saying that she has not gained any kinetic energy relative to the plane as she is not moving relative to it. However if she was not on the plane the amount of fuel used on take off would be slightly less and this additional fuel is what has given her the extra kinetic energy.