question_answer

Propulsion efficiency of a jet engine is given by(where u is flight velocity and V is jet velocity relative to aircraft):

A) \[\text{2}\,\text{u/}\left( \text{V}\,\,-\,\,\text{u} \right)\]                

B) \[\left( \text{V}\,\,\text{+}\,\,\text{u} \right)\text{/2}\,\text{u}\]

C) \[\text{2}\,\text{u/}\left( \text{V}\,\,\text{+}\,\,\text{u} \right)\]                 

D) \[\left( \text{V}\,\,-\,\,\text{u} \right)\text{/2}\,\text{u}\]