Answer:
18. 24/8 = 3
19. 50/12 = 4 and one-sixth
20. 18/16 = 1 and one-eighth
Explanation: I’m good at math
Answer: d) Prandtl number
Explanation: Prandtl number is basically defined as the ratio between the fluid's viscosity to the thermal conductivity.It doesn't have any sort of dimension. The fluids which are discovered with the small Prandtl numbers are considered as good fluids as they have a smooth rate of flow and as the number increases the fluid are not considered as reliable. Thus,option (d) is the correct option.
Answer:
a) Zero
b) the rate of entropy generation in the system's universe = ds/dt = 0.2603 KW/K
Explanation:
a) In steady state
Net rate of Heat transfer = net rate of heat gain - net rate of heat lost
Hence, the rate of heat transfer = 0
b) In steady state, entropy generated
ds/dt = - [ Qgain/Th1 + Qgain/Th2 - Qlost/300 K]
Substituting the given values, we get –
ds/dt = -[5/1500 + 3/1000 – (5+3)/300]
ds/dt = - [0.0033 + 0.003 -0.2666]
ds/dt = 0.2603 KW/K
To solve this problem we will start using the given temperature values and then transform them to the Kelvin scale. From there through the properties of the tables, described for the Air, we will find the entropy. With these three data we can perform energy balance and find the speed of the fluid at the exit, which will finally help us find the total force:





Using the tables for gas properties of air we can find the enthalpy in this two states, then


Applying energy equation to the entire engine we have that



Finally the force in terms of mass flow and velocity is



Therefore the thrust produced by this turbojet engine is 11971.168N