Newton's Second Law

· Newton's Second Law states that the force on an object is equal to the change in momentum of that object. In the case of a turbojet engine, the air mass flowing through the engine is experiencing the change in momentum.

· Since it is hard to judge the mass of a gas, such as the air being consumed by the engine, the mass flow rate is used in its place.

· The mass flow rate is given by:

Mass/Time = rVA

Where r is the density, V is the velocity, A is the area of the

air as it passes though the engine.