It's quite a long time since my Aero Eng degree but I can remember a few details. As jhorton said, I think you'll find that the exhaust gas leaves the engine at rather more than 190kts in most flight regimes.
There are actually two factors affecting engine thrust. These are the change in momentum of air passing through the engine, which you have already considered and also the stagnation pressure differential across the engine. If the exhaust gas is at a higher pressure than the ambient air, further thrust will be generated.
On most engines exhaust gas expands to equal the ambient pressure and accelerates so the pressure effect is zero. However on many military turbojets the exhaust nozzle becomes choked. This means that the exhaust has accelerated to Mach 1 (bear in mind that Mach 1 for the hot exhaust gas will be significantly faster than Mach 1 for the ambient air) and can accelerate no more. In this case, exhaust will leave the engine nozzle at its local speed of sound and at a higher than ambient pressure. In this situation the engine generates thrust both from momentum change and from pressure differential.
Geeky enough for you?