Thermodynamics
I.
Consider a system whose temperature is 18°C.
1. Temperature in K is ………………
a) 255
b) 291
c) 318
d) 354
c) 572.4
d) 637.2
c) 168.8
d) 177.8
2. Temperature in R is ……………….
a) 459
b) 523.8
3. Temperature in °F. is ………………
a) 55.4
II.
b) 64.4
The temperature of a system drops by 45°F during a cooling process.
4. The drop in temperature in K is ……………..
a) 25
b) 45
c) 48
d) 57
C) 48
d) 57
5. The drop in temperature in R is ……………..
a) 25
b) 45
6. The drop in temperature in °C is ……………..
a) 25
III.
b) 45
C) 48
d) 57
A gas is contained in a vertical, frictionless piston–cylinder device. The
piston has a mass of 4 kg and a cross-sectional area of 35 cm2. A
compressed spring above the piston exerts a force of 60 N on the piston.
The atmospheric pressure is 95 kPa.
7. The pressure inside the cylinder is ................. kPa.
a) 28.35
IV.
b) 66.65
C) 95.28
d)123.35
A 2000-kg car climbs a 100-m-long uphill road with a slope of 30°
(from horizontal) in 10 s. Disregard friction, air drag, and rolling
resistance.
8. The power required for this climbing, at constant velocity, is .............. kW.
a) 98.1
b) 170
C) 981
d) 1700
9. The power required for this climbing, from rest to a final velocity of 30 m/s,
is ....................... kW.
a) 101.1
b) 188.1
C) 173
d) 260
10. The power required for this climbing, from 35 m/s to a final velocity of 5 m/s,
is kW.
a) -290
V.
b) -21.9
C) 50
d) 218.1
A frictionless piston–cylinder device contains 2 kg of nitrogen at 100
kPa and 300 K. Nitrogen is now compressed slowly according to the
relation PV1.4 = constant until it reaches a final temperature of 360 K.
(Molecular weight of N2 is 28 g/mol)
11. The N2 Gas Constant is .................. J/kg.k.
a) 0.297
b) 297
C) 0.594
d) 594
12. The work input during this process is .................... kJ.
a) -178.2
b) -89.1
C) 89.1
d) 178.2
Nitrogen at an initial state of 300 K, 150 kPa, and 0.2 m3 is compressed
slowly in an isothermal process to a final pressure of 800 kPa.
VI.
13. The mass of N2 is .............. g.
a) 297
b) 337
C) 373
d) 733
14. The work done during this process is .......................... kJ.
a) -44
VII.
b) -50
C) 44
d) 50
0.1m3 of air is contained in a piston cylinder assembly at 1.5 bar and
27oC. It is first heated at constant volume until the pressure has
doubled, then it's expanded at constant pressure until the volume has
tripled.
15. The total work is .......................... kJ.
a) 0.06
b) 0.6
C) 6
d) 60
VIII. A piston-cylinder device contains 0.5 m3 helium gas at 150 kPa and
20oC. The helium is now compressed in a polytropic process to 400 kPa
and 140oC. (Molecular weight of helium is 4 g/mol)
16. The helium gas constant is ..................... J/kg.k.
a) 2078.5
b) 2.0785
C) 4.1572
d) 4157.2
C) 61.57
d) 0.06157
17. The mass of helium is ....................... g.
a) 0.12315
b) 123.15
18. The volume of helium is ............................... m3.
a) 0.192
b) 0.264
C) 0.528
d) 0.705
19. The index n for this polytropic process is …………
a) 1.025
b) 1.536
C) -1.025
d) -1.536
20. The work done during this process is .......................... kJ.
a) -1228.6
b) -114.61
C) -57.306
d) 57.306
C) 24
d) 38
IX.
21. For state (a), Q equals ……………
a) 2
b) 12
22. For state (a), E2 equals ……………
a) 14
b) 26
C) 24
d) 28
C) 15
d) 30
C) 25
d) 55
C) 30
d) 65
C) 35
d) 65
C) 3
d) 6
C) 21
d) 27
23. For state (b), W equals …………
a) -30
b) -15
24. For state (b), E2 equals …………..
a) -15
b) 15
25. For state (c), E1 equals ……………
a) 5
b) 15
26. For state (c), ΔE equals ……………
a) 15
b) 30
27. For state (d), W equals ……………..
a) -6
b) -3
28. For state (d), E1 equals ……………….
a) -27
b) -21
X.
An insulated piston-cylinder device contains 100 L of air at 400 kPa
and 25oC. A paddle wheel within the cylinder is rotated until 15 kJ of
work is done on the air while the pressure is held constant.
29. The mass of the air is ....................... g.
a) 429.2
b) 446.8
C) 467.7
d) 5575
30. The difference between the final and initial temperature is ....................... oC.
a) 25
b) 31.9
C) 56.9
d) 65.9
31. The pressure value of saturated liquid water at T=190 oC is .............. bar.
a) 12.27
b) 12.54
C) 12.82
d) 13.1
32. The specific enthalpy (h) value of saturated liquid water at T=190 oC is
……………… kJ/kg.
a) 806.2
b) 807.6
C) 810.6
d) 812.1
33. The specific internal energy (u) value of saturated liquid water at T=190 oC is
……………… kJ/kg.
a) 806.2
b) 807.6
C) 810.6
d) 812.1
34. The specific entropy (s) value of saturated liquid water at T=190 oC is
……………… kJ/kg.k.
a) 2.226
b) 2.236
C) 2.245
d) 2.255
35. The specific volume (υ) value of saturated liquid water at T=190 oC is
……………… m3/kg.
a) 0.001138
b) 0.001141
C) 0.001143
d) 0.001144
36. The dryness factor (x) value of saturated liquid water at T=190 oC is
…………
a) 0
b) 0.5
C) 0.9
d) 1
37. The temperature value of saturated vapor water at P=3bar is .............. oC.
a) 130.5
b) 131.5
C) 132.5
d) 133.5
38. The specific enthalpy (h) value of saturated vapor water at P=3bar is
……..………. kJ/kg.
a) 2542.19
b) 2543.37
C) 2723.68
d) 2725.25
39. The specific internal energy (u) value of saturated vapor water at P=3bar is
……..………. kJ/kg.
a) 2542.19
b) 2543.37
C) 2723.68
d) 2725.25
40. The specific entropy (s) value of saturated vapor water at P=3bar
…….kJ/kg.k.
a) 7.015
b) 7.004
C) 6.992
d) 6.981
41. The specific volume (υ) value of saturated vapor water at P=3bar …….
m3/kg.
a) 0.6063
b) 0.6258
C) 0.6468
d) 0.6692
42. The dryness factor (x) value of saturated vapor water at P=3bar is …………..
a) 0
b) 0.5
C) 0.9
d) 1
43. The specific enthalpy (h) value of water at P=20bar, T=150oC is
…………kJ/kg.
a) 631.1
b) 633.3
C) 676.5
d) 2798.71
44. The specific internal energy (u) value of water at P=20bar, T=150oC
is.…kJ/kg.
a) 631.1
b) 633.3
C) 676.5
d) 2583.23
45. The specific entropy (s) value of water at P=20bar, T=150oC is
….……kJ/kg.k.
a) 1.633
b) 1.738
C) 1.840
d) 1.941
46. The specific volume (υ) value of water at P=20bar, T=150oC is …………
m3/kg.
a) 0.001079
b) 0.00189
C) 0.001101
d) 0.001113
47. The phase of water at P=20bar, T=150oC is ………………
a) sub-cooled
XI.
b) liq.-vap. mix.
C) superheated
d) none
A closed, rigid tank contains 2 kg of water initially at 80°C and a
quality of 0.6. Heat transfer occurs until the tank contains only
saturated vapor. Kinetic and potential energy effects are negligible.
48. The specific internal energy of water before heating (u1) is ..................... kJ/kg.
a) 1623
b) 1719
C) 2147
d) 2482
49. The specific internal energy of water after heating (u2) is ..................... kJ/kg.
a)393.7
b) 2105
C) 2272
d) 2498
50. The amount of energy transfer by heat, in kJ, equals ………………
a) 784
b) 875
C) 1106
d) 1750