Thermodynamics / Heat Engineering Fundamentals TP. Hồ Chí Minh HUIT University

Fundamental Concepts of Units in Thermology Dynamics – Hard Practice Exam

100 questions

120 min

Answer key

Exam info

Subject: Thermodynamics / Heat Engineering Fundamentals
Exam type: University
Questions: 100
Duration: 120 min
Answers: ✓ With explanations
School: Đại học Công nghiệp TP.HCM (HUIT)

Questions (100)

Q 1.
Convert 250 oz into lb using the relationship .
- A.
  15.625 lb
- B.
  12.5 lb
- C.
  156.25 lb
- D.
  62.5 lb
Q 2.
Convert 80 lb into kg using .
- A.
  36.29 kg
- B.
  176.4 kg
- C.
  8.82 kg
- D.
  4536 kg
Q 3.
Convert 500 oz into lb.
- A.
  31.25 lb
- B.
  312.5 lb
- C.
  8 lb
- D.
  500 lb
Q 4.
The symbol 'm' typically represents mass in SI. What is the SI unit of mass and its definition as used in the chapter?
- A.
  kilogram (kg); 1 cm³ of water at its maximum density equals 1 g
- B.
  pound (lb); 1 lb equals 1 lb of water
- C.
  Newton (N); a measure of weight only
- D.
  kilogram-force (kgf); defined by weight
Q 5.
Convert 5 kg into lb using .
- A.
  11.025 lb
- B.
  2.267 lb
- C.
  110.25 lb
- D.
  0.441 lb
Q 6.
Convert 1500 g into oz using .
- A.
  52.905 oz
- B.
  5.2905 oz
- C.
  42525 oz
- D.
  529.05 oz
Q 7.
A refrigeration component is labeled '5 lb'. Convert this to kg.
- A.
  2.268 kg
- B.
  11.025 kg
- C.
  5 kg
- D.
  0.2268 kg
Q 8.
A 12-lb refrigerant cylinder has a mass of how many kg?
- A.
  5.443 kg
- B.
  26.46 kg
- C.
  0.5443 kg
- D.
  54.43 kg
Q 9.
A kilogram force (kgf) is defined as:
- A.
  The gravitational force acting on a mass of 1 kg at
- B.
  The force needed to accelerate 1 kg to the speed of light
- C.
  The force produced by 1 kg mass at the North Pole only
- D.
  Equal to 1 N by definition
Q 10.
Apply F = m·a. If a force of 1 N is exerted on a 1 kg mass for 1 s starting from rest, the final velocity is:
- A.
  1 m/s
- B.
  0 m/s
- C.
  9.807 m/s
- D.
  2 m/s
Q 11.
Calculate the weight in Newtons of a 10 kg mass using W = m·g with g = 9.807 m/s².
- A.
  98.07 N
- B.
  10 N
- C.
  9.807 N
- D.
  980.7 N
Q 12.
A technician weighs in at 70 kgf. Convert this weight to lbf using 1 kgf = 2.205 lbf.
- A.
  154.35 lbf
- B.
  31.75 lbf
- C.
  686.49 lbf
- D.
  7.14 lbf
Q 13.
Convert 50 N to kgf using .
- A.
  5.10 kgf
- B.
  490.35 kgf
- C.
  50 kgf
- D.
  0.510 kgf
Q 14.
A force of 20 kgf acts on a 5 kg mass. The acceleration produced is approximately:
- A.
  39.23 m/s²
- B.
  4 m/s²
- C.
  0.25 m/s²
- D.
  9.807 m/s²
Q 15.
On Earth, g_e = 9.807 m/s². What is the weight in kgf of a body whose mass is 25 kg?
- A.
  25 kgf
- B.
  245.175 kgf
- C.
  2.55 kgf
- D.
  0.255 kgf
Q 16.
The SI unit of pressure is the Pascal (Pa). 1 Pa equals:
- A.
- B.
- C.
- D.
Q 17.
A force of 100 N acts uniformly on an area of 0.5 m². The pressure is:
- A.
  200 Pa
- B.
  50 Pa
- C.
  500 Pa
- D.
  0.005 Pa
Q 18.
Pascal's Law states that pressure applied on a confined fluid is transmitted:
- A.
  Equally in all directions, regardless of chamber shape
- B.
  Only in the direction of applied force
- C.
  Decreasing with depth
- D.
  Only through solids
Q 19.
1 kgf/cm² is equal to how many psi?
- A.
  14.22 psi
- B.
  1 psi
- C.
  100 psi
- D.
  760 psi
Q 20.
The standard atmospheric pressure at sea level is 1 atm. In different units, this is:
- A.
  1.033 kgf/cm² = 101.3 kPa = 14.70 lbf/in² = 29.92 in.Hg = 760 mmHg
- B.
  0 kgf/cm² = 0 kPa = 0 mmHg
- C.
  14.22 kgf/cm² = 1000 kPa = 1 in.Hg
- D.
  1 psi = 7.031 kPa = 1 mmHg
Q 21.
Convert 20 kgf/cm² into atm using .
- A.
  19.356 atm
- B.
  20.66 atm
- C.
  1.936 atm
- D.
  193.56 atm
Q 22.
Convert 2 atm into kgf/cm².
- A.
  2.066 kgf/cm²
- B.
  1.9356 kgf/cm²
- C.
  0.5165 kgf/cm²
- D.
  20.66 kgf/cm²
Q 23.
Convert 1.5 kgf/cm² into mmHg.
- A.
  1103.4 mmHg
- B.
  1471.2 mmHg
- C.
  490.4 mmHg
- D.
  2.04 mmHg
Q 24.
Convert 745 mmHg into kgf/cm².
- A.
  1.013 kgf/cm²
- B.
  0.1013 kgf/cm²
- C.
  548 kgf/cm²
- D.
  745 kgf/cm²
Q 25.
Convert 12 kgf/cm² into kPa.
- A.
  1176.84 kPa
- B.
  122.4 kPa
- C.
  98.07 kPa
- D.
  11768.4 kPa
Q 26.
Convert 105 kPa into kgf/cm².
- A.
  1.071 kgf/cm²
- B.
  10.71 kgf/cm²
- C.
  10297.4 kgf/cm²
- D.
  0.1071 kgf/cm²
Q 27.
Convert 300 psi into kgf/cm².
- A.
  21.09 kgf/cm²
- B.
  2.109 kgf/cm²
- C.
  4266 kgf/cm²
- D.
  210.9 kgf/cm²
Q 28.
Convert 150 kPa into psi.
- A.
  21.75 psi
- B.
  1033.5 psi
- C.
  2175 psi
- D.
  2.175 psi
Q 29.
Convert 40 psi into kPa.
- A.
  275.8 kPa
- B.
  5.80 kPa
- C.
  27.58 kPa
- D.
  2758 kPa
Q 30.
Convert 28 psi into in.Hg.
- A.
  57.01 in.Hg
- B.
  13.75 in.Hg
- C.
  570.1 in.Hg
- D.
  5.70 in.Hg
Q 31.
Convert 62 in.Hg into psi.
- A.
  30.45 psi
- B.
  126.23 psi
- C.
  3.045 psi
- D.
  304.5 psi
Q 32.
What pressure does a column of air of 1 cm² cross-section from sea level to the upper atmosphere exert at the Earth's surface?
- A.
  1.033 kgf/cm² (14.70 lbf/in²)
- B.
  0 kgf/cm²
- C.
  100 kgf/cm²
- D.
  1 psi
Q 33.
A perfect vacuum is expressed numerically as:
- A.
  0 kgf/cm² = 0 mmHg = 0 Pa = 0 psi = 0 in.Hg
- B.
  1 atm in all units
- C.
  760 mmHg
- D.
  14.7 psi
Q 34.
Gauge pressure is calibrated to read:
- A.
  Zero at atmospheric pressure
- B.
  Zero at perfect vacuum
- C.
  1 atm always
- D.
  The absolute pressure directly
Q 35.
If a pressure gauge reads 8 kgf/cm² and atmospheric pressure is 1.033 kgf/cm², the absolute pressure is:
- A.
  9.033 kgf/cm²
- B.
  6.967 kgf/cm²
- C.
  8 kgf/cm²
- D.
  8.967 kgf/cm²
Q 36.
A vacuum gauge reads 20 in.Hg vacuum while atmospheric pressure is 29.92 in.Hg. What is the absolute pressure?
- A.
  9.92 in.Hg
- B.
  49.92 in.Hg
- C.
  20 in.Hg
- D.
  29.92 in.Hg
Q 37.
When the fluid pressure is greater than atmospheric pressure, the absolute pressure equals:
- A.
  Gauge pressure + atmospheric pressure
- B.
  Gauge pressure − atmospheric pressure
- C.
  Gauge pressure only
- D.
  Atmospheric pressure − gauge pressure
Q 38.
What is the absolute pressure (in psia) when a gauge reads 50 psig at sea level (P_atm = 14.7 psi)?
- A.
  64.7 psia
- B.
  35.3 psia
- C.
  50 psia
- D.
  14.7 psia
Q 39.
The three modes of heat transfer are:
- A.
  Conduction, convection, radiation
- B.
  Fusion, vaporization, sublimation
- C.
  Solid, liquid, gas
- D.
  Sensible, latent, specific
Q 40.
Which heat transfer mode requires no intervening medium?
- A.
  Radiation
- B.
  Conduction
- C.
  Convection
- D.
  Sublimation
Q 41.
Convection heat transfer occurs because heated fluid:
- A.
  Expands, becomes less dense, and rises
- B.
  Contracts and sinks, drawing heat downward
- C.
  Becomes heavier and rises
- D.
  Spreads only by electromagnetic waves
Q 42.
For conduction through a plane wall, the rate of heat transfer Q/t is given by:
- A.
- B.
- C.
- D.
Q 43.
In the Stefan-Boltzmann equation , the constant σ is:
- A.
  5.67 × 10⁻⁸ J/(s·m²·K⁴)
- B.
  9.807 m/s²
- C.
  1.055 Btu
- D.
  273 K
Q 44.
A surface has e = 0.5, A = 4 m², T = 500 K. Using with σ = 5.67 × 10⁻⁸ J/(s·m²·K⁴), what is H in watts? (500⁴ = 6.25 × 10¹⁰)
- A.
  7087.5 W
- B.
  14175 W
- C.
  708.75 W
- D.
  708750 W
Q 45.
Calculate the radiant energy emitted in 5 minutes by a body with H = 1417.5 W.
- A.
  425250 J
- B.
  4252.5 J
- C.
  7087.5 J
- D.
  4252.5 kJ
Q 46.
The Stefan-Boltzmann law gives energy as proportional to:
- A.
  (fourth power of absolute temperature)
- B.
  T (linear in T)
- C.
  (square of T)
- D.
  log T
Q 47.
A calorie (cal) is defined as the heat required to:
- A.
  Raise the temperature of 1 g of water by 1°C
- B.
  Raise 1 kg of water by 1°C
- C.
  Raise 1 lb of water by 1°F
- D.
  Raise 1 g of water by 100°C
Q 48.
A Btu is defined as:
- A.
  Heat required to raise 1 lb of water by 1°F
- B.
  Heat required to raise 1 kg of water by 1°C
- C.
  Heat required to raise 1 g of water by 1°C
- D.
  Heat required to melt 1 lb of ice
Q 49.
Convert 2500 cal into kcal.
- A.
  2.5 kcal
- B.
  2500 kcal
- C.
  0.0025 kcal
- D.
  25 kcal
Q 50.
Convert 5 kcal into cal.
- A.
  5000 cal
- B.
  5 cal
- C.
  50 cal
- D.
  0.005 cal
Q 51.
Convert 5 kcal into kJ.
- A.
  20.93 kJ
- B.
  2.093 kJ
- C.
  209.3 kJ
- D.
  1.194 kJ
Q 52.
Convert 100 kJ into kcal.
- A.
  23.89 kcal
- B.
  238.9 kcal
- C.
  418.6 kcal
- D.
  2.389 kcal
Q 53.
Convert 2500 kcal into Btu.
- A.
  9920 Btu
- B.
  630 Btu
- C.
  992000 Btu
- D.
  992 Btu
Q 54.
Convert 20000 Btu into kcal.
- A.
  5040 kcal
- B.
  79360 kcal
- C.
  50.4 kcal
- D.
  504 kcal
Q 55.
Convert 25000 Btu into kJ.
- A.
  26375 kJ
- B.
  2637.5 kJ
- C.
  23700 kJ
- D.
  263750 kJ
Q 56.
Convert 500 kJ into Btu.
- A.
  474 Btu
- B.
  527.5 Btu
- C.
  4740 Btu
- D.
  47.4 Btu
Q 57.
Convert 8000 J into kJ.
- A.
  8 kJ
- B.
  8000 kJ
- C.
  0.008 kJ
- D.
  80 kJ
Q 58.
Convert 2 kJ into J.
- A.
  2000 J
- B.
  2 J
- C.
  20 J
- D.
  0.002 J
Q 59.
1 calorie equals approximately:
- A.
  4.186 J
- B.
  1 J
- C.
  4186 J
- D.
  0.2389 J
Q 60.
Which pair correctly lists energy units used in different systems for the same quantity of heat?
- A.
  1 cal (conventional) ≈ 4.186 J (SI) ≈ 0.003968 Btu (yard-pound)
- B.
  1 cal ≈ 1 J ≈ 1 Btu
- C.
  1 kcal = 1 kJ = 1 Btu
- D.
  1 kJ = 1 kcal
Q 61.
On the Celsius scale, water freezes at:
- A.
  0°C
- B.
  32°C
- C.
  100°C
- D.
  273°C
Q 62.
On the Fahrenheit scale, water boils at:
- A.
  212°F
- B.
  100°F
- C.
  180°F
- D.
  32°F
Q 63.
Convert 100°C into Fahrenheit using F = (9/5)·C + 32.
- A.
  212°F
- B.
  100°F
- C.
  180°F
- D.
  132°F
Q 64.
Convert 50°F into Celsius.
- A.
  10°C
- B.
  50°C
- C.
  122°C
- D.
  18°C
Q 65.
At what temperature do the Celsius and Fahrenheit scales read the same value?
- A.
  −40°
- B.
  0°
- C.
  32°
- D.
  100°
Q 66.
Convert 0°C to Kelvin.
- A.
  273 K
- B.
  0 K
- C.
  32 K
- D.
  100 K
Q 67.
Convert 400 K to Celsius.
- A.
  127°C
- B.
  400°C
- C.
  673°C
- D.
  127 K
Q 68.
Convert −20°C to Kelvin.
- A.
  253 K
- B.
  −20 K
- C.
  293 K
- D.
  −253 K
Q 69.
Convert 20°F to Rankine.
- A.
  480 R
- B.
  20 R
- C.
  440 R
- D.
  540 R
Q 70.
Convert 200 R to Fahrenheit.
- A.
  −260°F
- B.
  200°F
- C.
  660°F
- D.
  −200°F
Q 71.
Absolute zero is defined as the temperature at which:
- A.
  All molecular motion stops
- B.
  Water freezes
- C.
  All gases become perfect vacuums
- D.
  Ice melts
Q 72.
Absolute zero is approximately:
- A.
  −273°C or 0 K or −460°F or 0 R
- B.
  0°C or 32°F or 273 K or 460 R
- C.
  100°C or 212°F or 373 K
- D.
  −40°C only
Q 73.
The Kelvin and Celsius scales:
- A.
  Have the same size of degree; differ by an offset of 273
- B.
  Have different degrees and different zeros
- C.
  Differ by a factor of 273
- D.
  Are exactly the same scale
Q 74.
The Rankine and Fahrenheit scales:
- A.
  Have the same size of degree; differ by an offset of 460
- B.
  Differ by a factor of 460
- C.
  Have different degree sizes
- D.
  Differ by an offset of 273
Q 75.
Convert 98.6°F (typical human body temperature) to Kelvin.
- A.
  310 K
- B.
  98.6 K
- C.
  210.8 K
- D.
  371.6 K
Q 76.
Dew point temperature is:
- A.
  The temperature at which air becomes saturated and water vapor condenses
- B.
  The boiling temperature of pure water
- C.
  Always 0°C
- D.
  The temperature of dry air only
Q 77.
At the dew point temperature, the relative humidity is:
- A.
  100%
- B.
  50%
- C.
  0%
- D.
  Depends on air composition
Q 78.
Wet-bulb temperature represents the:
- A.
  Total heat content of the air (sensible + latent)
- B.
  Sensible heat only
- C.
  Latent heat only
- D.
  Temperature of liquid refrigerant only
Q 79.
Dry-bulb temperature is NOT affected by:
- A.
  Vapor content or relative humidity of the air
- B.
  Ambient air temperature
- C.
  Time of day
- D.
  Local weather conditions
Q 80.
If dry-bulb equals wet-bulb, the air is:
- A.
  Saturated with moisture (100% RH)
- B.
  Very dry
- C.
  Superheated
- D.
  Subcooled
Q 81.
When humidity is low (dry air), the wet-bulb temperature is:
- A.
  Much lower than the dry-bulb temperature
- B.
  Equal to the dry-bulb temperature
- C.
  Higher than the dry-bulb temperature
- D.
  Equal to the dew-point temperature
Q 82.
As air temperature increases (at constant pressure), its ability to hold moisture:
- A.
  Increases
- B.
  Decreases
- C.
  Remains constant
- D.
  Drops to zero
Q 83.
Sweat evaporating from the skin provides cooling. Which condition reduces this cooling effect?
- A.
  High humidity
- B.
  Low humidity
- C.
  Strong wind
- D.
  Dry skin
Q 84.
Work is defined in physics as:
- A.
  Force multiplied by the distance through which it travels
- B.
  Force multiplied by time
- C.
  Mass multiplied by velocity
- D.
  Pressure multiplied by volume
Q 85.
Calculate the work done when a 100 N force moves its point of application 5 m.
- A.
  500 J
- B.
  20 J
- C.
  105 J
- D.
  5000 J
Q 86.
1 kgf·m is the amount of work done by:
- A.
  A force of 1 kgf moving its point of application 1 m
- B.
  A force of 1 N moving 1 m
- C.
  A mass of 1 kg falling 1 m
- D.
  1 kgf moving 1 cm
Q 87.
Energy is best defined as:
- A.
  The capacity or ability to do work
- B.
  The rate of doing work
- C.
  A force applied over an area
- D.
  Heat times temperature
Q 88.
Power is defined as:
- A.
  The time rate of doing work
- B.
  Force times distance
- C.
  Mass times acceleration
- D.
  Energy divided by volume
Q 89.
A 100 W motor runs for 60 seconds. The energy delivered is:
- A.
  6000 J
- B.
  600 J
- C.
  1.667 J
- D.
  60000 J
Q 90.
In refrigeration work, which three forms of energy are commonly considered?
- A.
  Mechanical, electrical, and heat
- B.
  Kinetic, potential, and chemical
- C.
  Solar, wind, and nuclear
- D.
  Latent, sensible, and specific
Q 91.
1 kgf·m equals approximately how many joules?
- A.
  9.807 J
- B.
  1 J
- C.
  0.1020 J
- D.
  98.07 J
Q 92.
When water at 0°C (ice) is warmed, the temperature will rise until:
- A.
  0°C, then stay constant while the ice melts
- B.
  100°C, then stay constant
- C.
  −273°C
- D.
  It immediately becomes vapor
Q 93.
The latent heat of vaporization of water at 100°C (atmospheric pressure) is approximately:
- A.
  539 kcal/kg
- B.
  100 kcal/kg
- C.
  334 kcal/kg
- D.
  2260 kcal/kg
Q 94.
Latent heat of fusion of water at 0°C is:
- A.
  79.6 kcal/kg
- B.
  539 kcal/kg
- C.
  100 kcal/kg
- D.
  0 kcal/kg
Q 95.
Sensible heat is heat that:
- A.
  Causes a change in temperature of a substance
- B.
  Causes a change of state with no temperature change
- C.
  Cannot be measured with a thermometer
- D.
  Is hidden in the substance
Q 96.
Latent heat is heat that:
- A.
  Causes a change of state without a change in temperature
- B.
  Always raises temperature
- C.
  Always lowers temperature
- D.
  Is unrelated to phase change
Q 97.
Sublimation is the phase change from:
- A.
  Solid directly to gas (skipping the liquid phase)
- B.
  Liquid to gas
- C.
  Solid to liquid
- D.
  Gas to liquid
Q 98.
A saturated vapor that is further heated (while separated from its liquid) becomes:
- A.
  A superheated vapor
- B.
  A saturated liquid
- C.
  A subcooled liquid
- D.
  An ideal gas only
Q 99.
Steam at 120°C and 1 atm. The saturation temperature at 1 atm is 100°C. The amount of superheat is:
- A.
  20°C
- B.
  100°C
- C.
  120°C
- D.
  220°C
Q 100.
A sub-cooled liquid exists at a temperature that is:
- A.
  Below the saturation temperature at the given pressure
- B.
  Above the saturation temperature
- C.
  Equal to the saturation temperature
- D.
  Above the critical temperature

Answers and explanations are in mode.