Identify the source which does not cause drag on a finite wing.

A)
Skin – friction
B)
Flow separation
C)
Trailing vortices
D)
Power provide by aircraft engine

Correct Answer :   Power provide by aircraft engine


Explanation : The flow over a wing has drag which comes from viscosity (skin – friction drag and pressure drag) plus drag induced by the trailing vortices. The power by the aircraft engine is used to overcome the drag and not cause it.