Answer:
D is the correct choice.
Explanation:
I'm assuming that this is probably a phase in the textbook or progarm you are studying, and this is just a matter of reading thoroughly.
Engineers usually benefit from catching a mistake, and would also benfit from keeping record of a misstep in order to remain clear of that mistake in the future.
Have a great day, and mark me brainliest if I am most helpful!
:)
Answer:
The change in enthalpy of helium is 4073.86kJ/kg
Explanation:
∆H = Cp(T2 - T1)
Cp = 3.5R = 3.5×8.314 = 29.099kJ/kgmolK ÷ 2 (1kgmol of helium = 2kg of helium) = 14.5495kJ/kgK, T2 = 300°C = 300+273K = 573K, T1 = 20°C = 20+273K = 293K
∆H = 14.5495kJ/kgK(573K - 293K) = 14.5495kJ/kgK × 280K = 4073.86kJ/kg
To solve this problem, we must simply use the concept of Total Energy transferred both in terms of work and heat. This is basically conjugated in the first law of thermodynamics.
If we take the heat absorbed as positive and the expelled as negative we have that the total work done in the heat engine is


For the case of the engine pumps the Energy absorbed is

In this way the ratio between the two would be

So it is reversible, because the state of efficiency of the body is totally efficient.
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.