![]() I'm writing this out for my own sake and for anyone else who might find this thread in the future, but please do let me know if it all sounds correct. So we end up with 5 * 9.8 = 4.9 kg per second one way or another. But because the gas was accelerated to 1000m/s only (because it cannot be accelerated any further as it has left the nozzle), the force will have acted on the 0.98 mass for 1000/5000 = 0.2 of a second. So when we say "the answer is 4.9 kg/s", what we're essentially saying is this: " irrespective of the rate of acceleration, if a certain mass was accelerated to 1,000 m/s over the course of one second by a force of 4900 Newtons, then that mass must have been equal to 4.9 kg."Īnd like you said, we can assume the acceleration to be anything. Once this dawned on me, things started making more sense. This is very important because it implies the velocity of the gas cannot increase beyond 1000m/s as there is no force acting on it any longer. Now that you've shown me a way to relate force to change in momentum, I can see where I was mistaken.Īlso, for some reason it did not occur to me that we were measuring the speed of the gas outside the nozzle. For some reason I was stuck thinking that unless acceleration is known, there's no way to determine anything about mass. These gases are then slowed using a diverging nozzle known as a diffuser these processes increase the pressure and temperature of the flow. In a practical gas turbine, gases are first accelerated in either a centrifugal or axial compressor. I think this is exactly what I was looking for. Together, these make up the Brayton cycle. We know that in some time interval #dt#, the fuel starts at rest and accelerates to #1000\text# or any other fraction, you will get the same force from the above equation. ![]()
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