You remember the assumption we made that across the disc velocity, axial velocity is constant everywhere. We made that assumptions still valued. So, for an elemental mass of fluid passing through an elemental area will be rho D A 0 V A plus V 1 across the disc. Is that correct? And what is the thrust, elemental thrust due to this area - d m into V A plus V 2 minus V A rate of change of momentum. So, you have rho D A 0 V A plus V 1 into V 2. Is that correct?