Thermodynamics - MCQs Part VIII

Compiled MCQs in Thermodynamics Part 8 of the series as one topic in General Engineering and Applied Sciences (GEAS) in the ECE Board Exam.

MCQs in Thermodynamics Part 8

This is the Multiples Choice Questions Part 8 of the Series in Thermodynamics as one of the General Engineering and Applied Sciences (GEAS) topic. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including past Board Questions in General Engineering and Applied Sciences (GEAS) field.

Online Questions and Answers in Thermodynamics Series

Following is the list of multiple choice questions in this brand new series:

MCQs in Thermodynamics
PART 1: MCQs from Number 1 – 50                        Answer key: PART I
PART 2: MCQs from Number 51 – 100                   Answer key: PART II
PART 3: MCQs from Number 101 – 150                 Answer key: PART III
PART 4: MCQs from Number 151 – 200                 Answer key: PART IV
PART 5: MCQs from Number 201 – 250                 Answer key: PART V
PART 6: MCQs from Number 251 – 300                 Answer key: PART VI
PART 7: MCQs from Number 301 – 350                 Answer key: PART VII
PART 8: MCQs from Number 351 – 400                 Answer key: PART VIII
PART 9: MCQs from Number 401 – 450                 Answer key: PART IX
PART 10: MCQs from Number 451 – 500                Answer key: PART X

Continue Practice Exam Test Questions Part VIII of the Series

351. A bayabas falls from a branch 5m above the ground with what speed in meter per second does it strike the ground assume g = 10m/s².

  • a. 11m/s
  • b. 12m/s
  • c. 13m/s
  • d. 10m/s

▲KE = mV2/2gc

352. While swimming a depth of 13m in a fresh water lake a fish emits an air bubble of volume 2 mm² atmospheric pressure is 100kpa what is the original pressure of the bubble.

  • a. 217.17 kpa
  • b. 119 kpa
  • c. 326.15 kpa
  • d. 210 kap

Pabs = Pg + Patm

353. Oxygen at 15ºC and 10.3 Mpa gauge pressure occupies 600L. What is the occupied by the oxygen at 8.28 Mpa gauge pressure and 35ºC?

  • a. 789.32 L
  • b. 796.32 L
  • c. 699 L
  • d. 588 L

V2= P1V1/T1P2

354. Water is flowing through a 1 foot diameter pipe at the rate of 10ft/sec. What is the volume flow rate of water in ft³/sec?

  • a. 7.85
  • b. 6.85
  • c. 8.85
  • d. 5.85

V = Aν

355. A certain fluid is flowing in a 0.5m x 0.3 channel at the rate of 3 m/s and has a specific volume of 0.012 m³/kg. Determined the mass of water flowing in kg/s.

  • a. 267 kg/s
  • b. 378 kg/s
  • c. 375 kg/s
  • d. 456.5 kg/s

m = Aν/V

356. A gas having a volume of100 ft³ at 27ºC is expanded to 120 ft³by heated at constant pressure to what temperature has it been heated to have this new volume?

  • a. 87°C
  • b. 85°C
  • c. 76°C
  • d. 97°C

t2= T2–T1

357. Water flow to a terminal 3 mm diameter and has an average speed of 2 m/s. What is the rate of flow in cubic meter/mm?

  • a. 0.0001m³/min
  • b. 0.076 m³/min
  • c. 0.085 m³/min
  • d. 0.097 m³/min

358. Water flowing at a 6m/s through a 60 mm pipe is suddenly channeled into a 30 mm pipe. What is the velocity in the small pipe?

  • a. 34m/s
  • b. 24m/s
  • c. 15m/s
  • d. 27m/s

359. A vertical column of water will be supported to what height by standard atmospheric pressure.

  • a. 33.9 ft
  • b. 45 ft
  • c. 67 ft
  • d. 25.46 ft

ho= Po/Yo

360. A fluid flows in a steady manner between two section in a flow line at section 1: A 1 = 1ft², V1 = 100fpm, volume1 of 4ft³/lb. at sec2: A2 = 2 ft², p= 0.20 lb/ft³ calculate the velocity at section 2.

  • a. 625 fpm
  • b. 567 fpm
  • c. 356 fpm
  • d. None of the above

361. The weight of an object is 50lb. What is its mass at standard condition?

  • a. 50 lbm
  • b. 60 lbm
  • c. 70 lbm
  • d. 80 lbm

formula: m = Fgk /g

362. A vertical column of water will be supported to what height by standard atmospheric pressure. If the Y w = 62.4lb/ft3 po = 14.7 psi.

  • a. 44.9 ft
  • b. 33.9 ft
  • c. 22.9 ft
  • d. 55.9 ft

formula: ho= po/Yw

363. For a certain gas R = 320 J/kg.K and cv= 0.84kJ/kg.K. Find k?

  • a. 1.36
  • b. 1.37
  • c. 1.38
  • d. 1.39

formula: k= R / cv+1

364. Ten cu. ft of air at 300psia and 400°F is cooled to 140°F at constant volume. What is the transferred heat?

  • a.-120Btu
  • b. -220Btu
  • c.-320Btu
  • d. -420Btu

formula: Q= mcv(T2-T1)

365. Utilizing the answer to the previous problem, estimate the overall or average increase in temperature ( ΔT) of the concrete roof from the energy absorbed from the sun during a12hour day. Assume that all of the radiation absorbed goes into heating the roof. The specific heat of concrete is about 900 J/kg, and the density is about 2,300 kg/m3.

  • a. 7.9 °C
  • b. 8.9°C
  • c. 9.9°C
  • d. 10.9°C

formula: ΔQ = m c ΔT

366. The concrete roof of a house is 10 m by 8 m and 10 cm thick (4"). Estimate the total heat the roof would absorb over the 12 day?

  • a. 1.3 x 108 J
  • b 2.3 x 108 J
  • c. 3.3 x 108 J
  • d. 4.3 x 108 J

formula: ΔQ = ΔQ/Δtx Δt

367. The value for the ΔU of a system is -120 J. If the system is known to have absorbed 420 J of heat, how much work was done?

  • a. -540 J
  • b. -640 J
  • c. -740 J
  • d. -840 J

formula: ΔU = q +w

368. When the pressure on a 1 kg liquid is increased isothermally from 1 bar to 3000 bar the Gibbs free energy increases by 360 kJ. Estimate the density of the liquid.

  • a. 0.66 kg liter-1
  • b. 0.77 kg liter-1
  • c. 0.88 kg liter-1
  • d. 0.99 kg liter-1

369. A car whose mass is 2 metric tons is accelerated uniformly from stand hill to 100 kmph in 5 sec. Find the driving force in Newton’s.

  • a. 11,120 N
  • b. 11,320 N
  • c. 11,420 N
  • d. 11520 N

formula: F= ma / k

370. An ideal gas of volume 1liter and pressure 10 bar undergoes a quasistatic adiabatic expansion until the pressure drops to 1 bar. Assume γ to be 1.4 what is the final volume?

  • a. 3.18 l
  • b. 4.18 l
  • c. 5.18 l
  • d. 6.18 l

371. Two masses, one of the 10kg and the other unknown, are placed on a scale in a region where g = 9.67 m/sec2. The combined weight of these two masses is 174.06 N. Find the unknown mass in kg.

  • a. 20 kg
  • b. 19 kg
  • c. 18 kg
  • d. 17 kg

formula: m=Fg k / g

372. The flow energy of 5 ft3 of a fluid passing a boundary to a system is 80,000 ft-lb. Determine the pressure at this point.

  • a. 222 psi
  • b. 333 psi
  • c. 444 psi
  • d. 111 psi

formula: Ef= pV

373. Find и for steam at 100 psia and 600°F.If h = 1329.6 and v = 6.216

  • a. 1214 Btu / lb
  • b. 1234 Btu /lb
  • c. 1342 Btu / lb
  • d. 1324 Btu /lb

formula: и = h– pv/ J

374. What mass of nitrogen is contained in a10 ft3 vessel at a pressure of 840atm and 820°R? Make a computation by using ideal gas equation.

  • a. 194lb
  • b. 214lb
  • c. 394 lb
  • d. 413lb

formula: m=pV /RT

375. A rotary compressor receives 6m3/ min of a gas(R=410J/ kgK, cp=1.03kJ /kgK,k= 1.67) at 105 k/Paa, 27°C and delivers it at 630kPaa: ΔP = 0, ΔK= 0. Find the work if the process is isentropic?

  • a. –1664 kJ/min
  • b. –1774 kJ/min
  • c. –1884 kJ/min
  • d. –1994 kJ/min

formula: WSF = Q- ΔH m=p1V1/RT1 T2= T1(p2/p1)(k-1)/k

376. A carnot power cycle operates on 2 lb of air between the limits of 71 °F and 500°F. The pressure at the beginning of isothermal expansion is 400 psia and at the end of isothermal expansion is 185psig. Determine the volume at the end of isothermal compression.

  • a. 7.849 ft3
  • b. 7.850 ft3
  • c. 7.851 ft3
  • d. 7852 ft3

formula: V= mRT/ P P3= P2[T3/ T2]

377. During a polytropic process,10lb of an ideal gas, whose R= 40ft.lb/lb.R and cp = 0.25Btu/lb.R, changes state from 20 psia and 40°F to 120psia and 340°F. Determine n?

  • a. 1.234
  • b. 1.345
  • c. 1.456
  • d. 1.356

formula: [ p2/p1]n-1 / n = T2/T1

378. A perfect gas has a value of R= 319.2 J/ kf.K and k= 1.26. If 120 kJ are added to 2.27 kf\g of this gas at constant pressure when the initial temp is 32.2°C? Find T2.

  • a. 339.4 K
  • b. 449.4 K
  • c. 559.4K
  • d. 669.4K

formula: cp = kR/ k-1 Q= mcp(T2-T1)

379. A certain gas, with cp = 0.529Btu/ lb. °Rand R = 96.2ft.lb/lb. °R, expands from 5 cu ft and 80°F to 15 cu ft while the pressure remains constant at 15.5psia. Compute for T2.

  • a.1520°R
  • b. 1620°R
  • c. 1720°R
  • d. 1820°R

formula: T2= T1V2/V1

380. A System has a temperature of 250°F. Convert this Value to °R?

  • a. 740°R
  • b.730°R
  • c. 720°R
  • d. 710°R

formula: °R= °F + 460

381. Steam with a specific volume of 0.09596 m³/kg undergoes a constant pressure process at 1.70 MPa until the specific volume becomes 0.13796 m³/kg. What are (a) the final temperature, (b) ∆u, (c) W, (d)∆s, and (e) Q?

  • a) 265.4°C, 430.7kJ/kg, 71.4kJ/kg, 1.0327kJ/(kg)(K),502.1 kJ/kg
  • b) 204.2°C, -703.2 kJ/kg, -84.15 kJ/kg, -1.7505 kJ/(kg)(K), -787.4 kJ/kg
  • c) 304.2°C, -803.2 kJ/kg, -89.15 kJ/kg, -2.7505 kJ/(kg)(K), -987.4 kJ/kg
  • d) 279.4°C, 439.7kJ/kg, 79.4kJ/kg, 3.0327kJ/(kg)(K),602.1 kJ/kg

382. Steam with an enthalpy of 2843.5 kJ/kg undergoes a constant pressure process at 0.9 MPa until the enthalpy becomes 2056.1 kJ/kg. What are (a) the initial temperature or quality, (b) ∆u, (c)W, (d) ∆s, and(e) Q?

  • a) 265.4°C, 430.7kJ/kg, 71.4kJ/kg, 1.0327kJ/(kg)(K),502.1 kJ/kg
  • b) 204.2°C, -703.2 kJ/kg, -84.15 kJ/kg, -1.7505 kJ/(kg)(K),-787.4 kJ/kg
  • c) 304.2°C, -803.2 kJ/kg, -89.15 kJ/kg, -2.7505 kJ/(kg)(K), -987.4 kJ/kg
  • d) 279.4°C, 439.7kJ/kg, 79.4kJ/kg, 3.0327kJ/(kg)(K), 602.1 kJ/kg

Formula of #1and #2: ∆u = u2 –u1, W = p(v2-v1), ∆s =s2-s1, Q = h2 –h1

383. At throttling calorimeter receives steam from a boiler drum at0.11MPa and is superheated by 10 degrees. If the boiler drum pressure is 1.55 MPa, what is the quality of the steam generated by the boiler?

  • a) 95.20%
  • b) 70.10%
  • c) 65.60%
  • d) 95.56%

Formula: h1 = hf1 + x1hfg1

384. A steam calorimeter receives steam from a pipe at 0.1 MPa and 20°SH. For a pipe steam pressure of 2 MPa, what is the quality of the steam?

  • a) 95.56%
  • b) 70.10%
  • c) 95.20%
  • d) 85.10%

Formula: h1 = hf1 + x1hfg1

385. A 1-kg steam-water mixture at 1.0 MPa is contained in an inflexible tank. Heat is added until the pressure rises to 3.5 MPa and the temperature to 400°. Determine the heat added.

  • a) 1378.7 kJ
  • b) 1348.5 kJ
  • c) 1278,7 kJ
  • d) 1246,5 kJ

Formula: Q = (h2 – p2v2) –(h1 –p1v1)

386. Water vapor at 100 KPa and 150°C is compressed isothermally until half the vapor has condensed. How much work must be performed on the steam in this compression process per kilogram?

  • a) -1384.7 kJ
  • b) 1384.7 kJ
  • c) -2384.7 kJ
  • d) 2384.7 kJ

387. Wet steam at 1 MPa flowing through a pipe is throttled to a pressure of 0.1 MPa. If the throttling temperature is110°C, What is the quality of the steam in the pipe?

  • a) 96%
  • b) 86%
  • c) 76%
  • d) 66%

388. Steam is throttled to 0.1 MPa with 20 degrees of superheat. (a) What is the quality of throttled steam if its pressure is 0.75 MPa (b) What is the enthalpy of the process?

  • a) 97.6%,2713 kJ/kg
  • b) -97.6%, 2713 kJ/kg
  • c) 87.6%,3713 kJ/kg
  • d) -87.6%, 3713 kJ/kg

389. The pressure gauge on a 2000 m³ tank of oxygen gas reads 600 kPa. How much volumes will the oxygen occupied at pressure of the outside air 100 kPa?

  • a) 14026.5 m³
  • b) 15026.5 m³
  • c) 13026.5 m³
  • d) 16026.5 m³

Formula: P1V1/T1 =P2V2/T2

390. Assuming compression is according to the Law PV = C, Calculate the initial volume of the gas at a pressure of 2 bars w/c will occupy a volume of 6m³ when it is compressed to a pressure of 42 Bars.

  • a) 130m³
  • b) 136m³
  • c) 120m³
  • d) 126m³

Formula: P1V1/T1 =P2V2/T2

391. A Gas tank registers1000 kPa. After some gas has been used, the gauge registers 500 kPa. What percent of the gas remains in the tank?

  • a) 64.40%
  • b) 74.60%
  • c) 58.40%
  • d) 54.60%

Formula: Pabs = Patm + Pgage & %= P2/P1 * 100%

392. The volume of a gas under standard atmospheric pressure & 76 cmHg is 200m³. What is the volume when pressure is 80 cmHg if the temperature is unchanged?

  • a) 180 in³
  • b) 170 in³
  • c) 160 in³
  • d) 190 in³

Formula: P2V2 = P1V1

393. While swimming at depth of120m in a fresh water lake, A fish emits an air bubbles of volume 2.0mm³ atmospheric pressure is 100kPa. What is the pressure of the bubble?

  • a) 217.7 kPa
  • b) 317.7 kPa
  • c) 417.7 kPa
  • d) 517.7 kPa

Formula: P= δh

394. How many joules of work is the equivalent of 15000 cal of heat?

  • a) 62850 joules
  • b) 3579.95 joules
  • c) 14995.81 joules
  • d) 15004.19 joules

Formula: J =Work/Heat

J = mechanical equivalent of heat whose value is 4.19 joules/calorie

395. Two thick slices of bread, when completely oxidized by the body, can supply 200,000 cal of heat. How much work is this equivalent to?

  • a) 4,190,000 joules
  • b) 8,390,000 joules
  • c) 839,000 joules
  • d) 419 000 joules

Formula: J =Work/Heat

J = mechanical equivalent of heat whose value is 4.19 joules/calorie

396. 3 horsepower (hp) = _____________watts?

  • a) 1492 watts
  • b) 2238 watts
  • c) 746 watts
  • d) 2238 kilowatts

Formula: 1hp= 746 watts

397. How many Newton’s (N) in 900,000 dynes?

  • a) 8 Newton’s
  • b) 9 Newton’s
  • c) 7 Newton’s
  • d) 6 Newton’s

Formula: 1Newton (N)=100,000dynes

398. Calculate the power output in horsepower of an 80-kg man that climbs a flight of stairs 3.8 m high in 4.0 s.

  • a) 744.8 hp
  • b) 0.998 hp
  • c) 746 hp
  • d) 1.998 hp

Formula: Power = Fd/t = mgh/t

F = W = mg

d = h

399. How many calories of heat will be needed to raise the temperature of 200 g of iron from 27°C to 80°C? (c = 0.11 cal/g. °C)

  • a) 1.16 kcal
  • b) 2166 cal
  • c) 3.16 kcal
  • d) 4166 cal

Formula: H = mc∆T

400. 100g of iron was heated to 100°C and mixed with 22g of water at 40°C. The final temperature of the mixture was 60°C. Show that the heat given off by the iron equals the heat absorbed by the water.

  • a) 440 cal
  • b) 540 cal
  • c) 340 cal
  • d) 640 cal

Formula: H (given off by iron) = H (absorbed by water),

mc∆T(iron)= mc∆T(water)

Complete List of MCQs in General Engineering and Applied Science per topic


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