How a Turbojet Produces

Thrust

Picture from: http://www.lerc.nasa.gov/WWW/K-12/airplane/thrsteq.html

· The thrust a turbojet produces is the force equal to the mass flow rate of the exhaust air multiplied by the velocity of the exhaust air minus the value of the mass flow rate of the inlet air multiplied by the velocity of the exhaust air.

· Therefore, the thrust an aircraft produces is equal to the change in momentum of the air from the time that it enters the engine to the time that it exits the engine.