Introduction to Engineering

Post ID: 3028227

Overview

1. PLEASE ANSWER FOLLOWING QUESTIONS
2. Which of the following is not a control volume?
  1. insulated tank
  2. car radiator
  3. compressor
  4. turbine
3. Flow in a pipe is assumed to be uniform. The x-coordinate is along the pipe and r is the radial coordinate. Which of the following is not true?
  1. v = v(r)
  2. v = v(x)
  3. v = v(t)
  4. v = const.
4. Liquid water flows in the pipe at 12 m/s. The pipe’s diameter is reduced by a factor of 2. What is the velocity in the reduced section?
  1. 36 m/s
  2. 48 m/s
  3. 24 m/s
  4. 3 m/s
5. A nozzle accelerates steam at 4 MPa and 500°C to 1 MPa and 300°C. If V1 = 20 m/s, the exiting velocity is nearest:
  1. 575 m/s
  2. 750 m/s
  3. 825 m/s
  4. 890 m/s
6. Calculate the mass flow rate at the nozzle exit of Question 4 if d1 =10 cm.
  1. 2.9 kg/s
  2. 2.3 kg/s
  3. 1.8 kg/s
  4. 1.1 kg/s
7. Air in the amount of 100 kg/min enters a tube at 25°C and leaves at 20°C. The heat loss is nearest:
  1. 750 kJ/min
  2. 670 kJ/min
  3. 500 kJ/min
  4. 480 kJ/min
8. Calculate the power needed to raise the pressure of water 4 MPa assuming the temperature remains constant. The mass flux is 5 kg/s and ˙Q=0�˙=0.
  1. 20 kW
  2. 32 kW
  3. 48 kW
  4. 62 kW
9. Which of the following is usually assumed to be reversible?
  1. paddle wheel
  2. compressing a gas
  3. melting an ice cube
  4. a burst membrane
10. A Carnot engine operates between reservoirs at 20°C and 200°C. If 10 kW of power is produced, the rejected heat rate is nearest:
  1. 26.3 kJ/s
  2. 20.2 kJ/s
  3. 16.3 kJ/s
  4. 12 kJ/s
11. An inventor invents a thermal engine that operates between ocean layers at 27°C and 10°C. It produces 10 kW and discharges 9900 kJ/min of heat. Such an engine is:
  1. impossible
  2. reversible
  3. possible
  4. probable
12. Select the Kelvin–Planck statement of the second law.
  1. An engine cannot produce more heat than the heat it receives.
  2. A refrigerator cannot transfer heat from a low-temperature reservoir to a high-temperature reservoir without work.
  3. An engine cannot produce work without discharging heat.
  4. An engine discharges heat if the work is less than the heat it receives.
13. Select the incorrect statement relating to a Carnot cycle.
  1. There are two adiabatic processes.
  2. There are two constant pressure processes.
  3. Each process is a reversible process.
  4. Work occurs in all four processes.
14. A Carnot refrigerator requires 10 kW to remove 20 kJ/s from a 20°C reservoir. What is TH?
  1. 440 K
  2. 400 K
  3. 360 K
  4. 340 K
15. Find ΔSnet if a 10-kg copper mass at 100°C is submerged in a 20°C lake.
  1. 1.05 kJ/K
  2. 0.73 kJ/K
  3. 0.53 kJ/K
  4. 0.122 kJ/K
16. Find the maximum work output from a steam turbine if P1 = 10 MPa, T1 = 600°C, and P2 = 40 kPa.
  1. 1625 kJ/kg
  2. 1545 kJ/kg
  3. 1410 kJ/kg
  4. 0.1225 kJ/kg
17. Find the minimum work input to an air compressor if P1 = 100 kPa, T1 = 27°C, and P2 = 800 kPa.
  1. 276 kJ/kg
  2. 243 kJ/kg
  3. 208 kJ/kg
  4. 187 kJ/kg
18. The entropy change while expanding air in a cylinder from 800 kPa is 0.2 kJ/kg·K. If the temperature remains constant at 27°C, what is the heat transfer?
  1. 140 kJ/kg
  2. 115 kJ/kg
  3. 100 kJ/kg
  4. 60 kJ/kg
19. Find the maximum outlet velocity for an air nozzle that operates between 400 kPa and 100 kPa if T1 = 27°C.
  1. 570 m/s
  2. 440 m/s
  3. 380 m/s
  4. 320 m/s
20. The efficiency of an adiabatic steam turbine operating between P1 = 10 MPa, T1 = 600°C, and P2 = 40 kPa is 80%. What is u2?
  1. 2560 kJ/kg
  2. 2484 kJ/kg
  3. 2392 kJ/kg
  4. 2304 kJ/kg
21. The efficiency of an adiabatic air compressor operating between P1 = 100 kPa, T1 = 27°C, and T2 = 327°C is 80%. What is P2?
  1. 540 kPa
  2. 680 kPa
  3. 720 kPa