Answer:
a)
, b)
, c) Irreversible.
Explanation:
a) The power input required by the refrigerator is:



b) The Coefficient of Performance of the refrigerator is:



c) The maximum ideal Coefficient of Performance of the refrigeration is given by the inverse Carnot's Cycle:



The refrigeration cycle is irreversible, as
.
Answer:
We choose PTFE
Explanation:
Attached are the modulus density and modulus strength chart.
Due to its young modulus, the density is near 0.5 GPa, as seen in the chart and support water gliding. The PTFE density is between 1 and 10 Mg / cubic meter (see module and chart of density), and the resistance is between 10 and 100 Mpa (see module and chart of strength). Therefore, the finest ploymer will be PTFE that meets the requirements.
Answer: new depth will be 3.462m and the water elevation will be 0.462m.
The maximum contraction will be achieved in width 0<w<3
Explanation:detailed calculation and explanation is shown in the image below