Homework answers / question archive / University of Alabama, Birmingham - ELC 101 1)Convert the change of temperature from 20?C to 30?C to Kelvin scale

University of Alabama, Birmingham - ELC 101 1)Convert the change of temperature from 20?C to 30?C to Kelvin scale

Electrical Engineering

Share With

---

University of Alabama, Birmingham - ELC 101

1)Convert the change of temperature from 20?C to 30?C to Kelvin scale.

a.         a. 10 K

b.         b. 293 K

c.         c. 303 K

d.         d. 273 K

2.                    is a thermodynamic potential which measures the “useful” work obtainable from a closed thermodynamic system at a constant temperature and volume.

a.         a. useful work

b.         b. energy consumed

c.         c. Helmholtz free energy

d.         d. Kinetic Energy

3.         How much will the length of a 1.0 km section of concrete highway change if the temperature varies from -15?C in winter to 41?C in summer?

a.         a. 0.67 m

b.         b. 2.2 m

c.         c. 3.1 m

d.         d. 0.47 m

4.         Two 12 ft. sections of aluminum siding are placed end to end on the outside wall of house. How large a gap should be left between the pieces to prevent buckling if the temperature can change by 55?C?

a.         a. 0.21 m

b.         b. 0.18 m

c.         c. 0.31 in

d.         d. 0.18 in

5.         What is the amount of radiant energy received each second over each square meter that is at right angles to the sun’s rays at the top of the atmosphere?

a.         a. 1400 J

b.         b. 6000 J

c.         c. 10000 J

d.         d. 800 J

6.                    is a thermodynamic potential that measures the “useful” or process-initiating work obtainable from an isothermal, isobaric thermodynamic system.

a.         a. Du-Pont Potential

b.         b. Gibbs free energy

c.         c. Rabz-Eccles Energy

d.         d. Claussius Energy

7.         All the energy we consume ultimately becomes       .

a.         a. heat

b.         b. depleted

c.         c. exhausted

d.         d. work

8.                    is the partial pressure of water vapor at the existing temperature divided by the equilibrium vapor pressure of water at the existing temperature.

a.         a. vacuum pressure

b.         b. relative humidity

without a bulk movement of the material.

c.         a. Convection

 

d.         c. absolute pressure

e.         d. vapor pressure

9.                    is the transition of a given substance from the solid to the gas phase with no intermediate liquid stage.

a.         a. Convection

b.         b. Conduction

c.         c. Radiation

d.         d. Sublimation

10.       A process in which heat energy is transferred by the flow of fluid.

a.         a. Convection

b.         b. Conduction

c.         c. Radiation

d.         d. Sublimation

11.       In order to use a substance to make a thermometer the substance must    with a temperature change.

a.         a. expand

b.         b. contract

c.         c. change

d.         d. increase

12.       For most solids, the coefficient of volume expansion is

            the coefficient of linear expansion.

a.         a. unrelated to

b.         b. proportional to

c.         c. twice

d.         d. three times

13.       The volume of a given amount of water        as the temperature decreases from 4?C to 0?C.

a.         a. decreases

b.         b. increases

c.         c. remains constant

d.         d. none of the above

14.       The gas in a constant gas thermometer cooled to absolute zero would have          .

a.         a. no volume

b.         b. no pressure

c.         c. zero temperature at all scales

d.         d. none of the above

15.       On a day when the partial pressure of water vapor remains constant, what happens as the temperature rises?

a.         a. the relative humidity increases

b.         b. the relative humidity decreases

c.         c. the relative humidity remains constant

d.         d. the air would eventually become saturated

16.       The flow of a fluid when heat is transferred by convection.

a.         a. placidity

b.         b. mass flow

c.         c. convection current

d.         d. heat transfer

17.       An idealized perfect absorber and perfect emitter of radiation.

a.         a. elastic material

b.         b. transponder material

c.         c. Teflon

d.         d. blackbody

18.       A process by which heat is transferred through a material

 

a.         b. Conduction

b.         c. Radiation

c.         d. Emission

19.       Is the amount of a substance that contains Avogadro’s number of atoms/molecules.

a.         a. mass

b.         b. matter

c.         c. gram-mole

d.         d. volume

20.       The distribution of particle speeds in an ideal gas at a given temperature.

a.         a. velocity of propagation

b.         b. escape velocity

c.         c. Maxwell speed Distribution

d.         d. terminal velocity

21.       A convection process in which an external device, such as a fan, is used to produce the fluid flow.

a.         a. Forced Convection

b.         b. External Convection

c.         c. Placid Convection

d.         d. Thermionic Convection

22.       A          is a quantity whose value at any state is independent of the path or process used to reach that state.

a.         a. cycle

b.         b. path function

c.         c. point function

d.         d. process

23.       A          is a quantity whose value depends on the path followed during a particular change in state.

a.         a. path function

b.         b. point function

c.         c. process

d.         d. cycle

24.       The contact surface shared by both the system and the surroundings is called       .

a.         a. wall

b.         b. boundary

c.         c. interface

d.         d. intersection

25.       A closed system is also known as       .

a.         a. isolated system

b.         b. closed container

c.         c. control mass

d.         d. control volume

26.       Open system is also known as            .

a.         a. isolated system

b.         b. closed container

c.         c. control mass

d.         d. control volume

27.       Liquid hydrogen boils at 17 K. What is the temperature in degrees Celsius?

a.         a. 290

b.         b. 63

c.         c. -120

d.         b. entropy

 

e.         d. -256

28.       When a solid melts,

a.         a. the temperature of the substance increases.

b.         b. the temperature of the substance decreases.

c.         c. heat leaves the substance.

d.         d. heat enters the substance.

29.       How many kilocalories of heat are required to heat 750 g of water from 35?C to 55?C.

a.         a. 15

b.         b. 1500

c.         c. 1.5 x 10^4

d.         d. 6.3 x 10^4

30.       Which of the following does not determine the amount of internal energy an object has?

a.         a. temperature

b.         b. amount of material

c.         c. type of material

d.         d. shape of the object

31.       Which of the following have the highest thermal conductivities?

a.         a. liquids

b.         b. gases

c.         c. metals

d.         d. solids other than metals

32.       Identical objects of four different materials are heated to the same high temperature. Which of the following would least likely burn your hand if touched?

a.         a. aluminium

b.         b. brass

c.         c. glass

d.         d. concrete

33.       As we heat a gas at constant pressure, its volume

a.         a. increases

b.         b. decreases

c.         c. stays the same

d.         d. none of the above

34.       The volume of an ideal gas is directly proportional to its

a.         a. pressure

b.         b. Celsius temperature

c.         c. Kelvin temperature

d.         d. Fahrenheit temperature

35.       An ideal gas is maintained at constant temperature. If the pressure on the gas is doubled, the volume is

a.         a. increased fourfold

b.         b. doubled

c.         c. reduced by half

d.         d. decreased by a quarter

36.       If the Kelvin temperature of an ideal gas is doubled, what happens to the rms speed of the molecules in the gas?

a.         a. it increases by a factor of square root of 2

b.         b. it increases by a factor of 2

c.         c. it increases by factor of 4

d.         d. none of the above

37.       A function of state that is associated with disorder in the system and environment.

a.         a. enthalpy

 

b.         c. law of diminishing return

c.         d. Lenz’ Law

38.       No volume changes occur during this type of process

a.         a. Isobaric process

b.         b. Isomillimetric process

c.         c. Isocaloric process

d.         d. Isochoric process

39.       The boiling of water into steam in an open container is an example of a/an          process.

a.         a. adiabatic

b.         b. isochoric

c.         c. isobaric

d.         d. zero work

40.       When liquid water is converted to steam at 100?C, the entropy of water

a.         a. increases

b.         b. decreases

c.         c. remains the same

d.         d. none of the above

41.       Only energy can cross the boundaries.

a.         a. Closed system

b.         b. Open system

c.         c. Isolated system

d.         d. Isoenergetic system

42.       The temperature at which the vapor pressure exactly equals one atm is called     .

a.         a. boiling temperature

b.         b. normal boiling point

c.         c. triple point

d.         d. point of infliction

43.       Mixture of liquid and steam of the same substance in which both are at saturation temperature.

a.         a. dry steam

b.         b. current steam

c.         c. wet steam

d.         d. aerosol

44.       The term         is traditionally used to describe steam issuing from condensate receiver vents and open-ended condensate discharge lines from steam traps.

a.         a. dry steam

b.         b. wet steam

c.         c. phase steam

d.         d. flash steam

45.       Defined as the ratio of weight of dry steam to the weight of stuff.

a.         a. dryness fraction

b.         b. Vaporization

c.         c. fusion

d.         d. super heated steam

46.       What device measures infrared radiation below?

a.         a. thermocouple

b.         b. thermopile

c.         c. thermodynamic device

d.         d. thermos

47.       When an object undergoes thermal expansion,

a.         d. 87.2 x 10^4 N/m^2

 

b.         a. any holes in the object expand as well

c.         b. any holes in the object remain the same

d.         c. mass increases

e.         d. molecular activities would cease

48.                  is the quantity of heat required to raise the temperature of one pound of water 1 F? from 63 ?F to 64 ?F.

a.         a. one Joule

b.         b. one calorie

c.         c. one watt

d.         d. one BTU

49.       Boiling temperature of a material is dependent on its

            .

a.         a. volume

b.         b. power

c.         c. heat

d.         d. pressure

50.       Thermos was invented by       .

a.         a. Sir Arthur Conan Doyle

b.         b. Sir Fredrich the Great

c.         c. Thomas Edison

d.         d. Sir James Dewar

51.       Most cooking activities involve          process.

a.         a. Isochoric

b.         b. Isothermal

c.         c. Isobaric

d.         d. Isovolumic

52.       Adiabatic heating and Adiabatic cooling really means

            and      respectively.

a.         a. raising the temp and lowering the temp

b.         b. maintaining the pressure and changing the temperature

c.         c. decreasing the volume and increasing the pressure

d.         d. lowering the temp and raising the temp

53.       The statement “heat cannot by itself flow from one body into a hotter body” is governed by        .

a.         a. the first law of thermodynamics

b.         b. the second law of thermodynamics

c.         c. the third law of thermodynamics

d.         d. the zeroth law of thermodynamics

54.       It is impossible for any process to have as its sole result the transfer of heat from a cooler to a hotter body

a.         a. Carnot’s statement

b.         b. Clausius statement

c.         c. Rankine statement

d.         d. Gauss statement

55.                  is the average distance a molecule moves before colliding with another molecule.

a.         a. mean free path

b.         b. path allowance

c.         c. compacting factor

d.         d. molecular space

56.       Find the pressure due to a column of mercury 74.0 cm high.

a.         a. 91.80 x 10^3 N/m^2

b.         b. 73.56 x 10^2 N/m^2

c.         c. 9.86 x 10^4 N/m^2

 

57.       Roughly what is the total weight of air in the entire earth?

a.         a. 1 x 10^5 tons

b.         b. 2 x 10^6 tons

c.         c. 6 x 10^15 tons

d.         d. 8 x 10^10 tons

58.                  is defined as that equivalent to the pressure due to a column of mercury 76cm long.

a.         a. surface pressure

b.         b. gage pressure

c.         c. standard atmospheric pressure

d.         d. isobaric pressure

59.       If any external pressure is applied to a confined fluid, the pressure will be increased at every point in the fluid by the amount of the external pressure is known as           .

a.         a. Torricelli’s law

b.         b. Barometric law

c.         c. Newton’s Second law

d.         d. Pascal’s law

60.       What type of pressure cannot be used for Boyle’s Law?

a.         a. Atmospheric Pressure

b.         b. Gauge Pressure

c.         c. Surface Pressure

d.         d. Isobaric Pressure

61.       To displace a cubic foot of fresh water, you need    

force.

a.         a. 62.4 lb

b.         b. 9.81 lb

c.         c. 76 lb

d.         d. 760 lb

62.       The force per unit length across such a line in the surface is called .

a.         a. force per length

b.         b. surface tension

c.         c. Pressure

d.         d. Density

63.       The speed at which a liquid escapes from a vessel through an orifice is given by   .

a.         a. Archimedes Principle

b.         b. Evangelista’s Law

c.         c. Torricelli’s Theorem

d.         d. Bernoulli’s Equation

64.       The process of one substance mixing with another because of molecular motion is called            .

a.         a. diffusion

b.         b. viscosity

c.         c. streamline flow

d.         d. solution

65.       When was the Ninth General Conference on Weights and Measures decided to abandon centigrade and used Celsius Instead?

a.         a. 1950

b.         b. 1936

c.         c. 1957

d.         d. 1948

66.                  is the temperature to which the air must be 180?C and exhausts directly into the air at 100?C. What is the upper limit of its efficiency?

 

cooled, at constant pressure, to produce saturation.

a.         a. relative humidity

b.         b. triple point temperature

c.         c. dew point

d.         d. critical point

67.                  is a succession of changes that ends with the return of the body or system to its initial state.

a.         a. process

b.         b. system

c.         c. equilibrium

d.         d. cycle

68.       Intensive properties of a system are called   .

a.         a. Bulk Properties

b.         b. Innate Properties

c.         c. Natural Properties

d.         d. Inside Properties

69.       In thermodynamics, a throttling process, also called a

            , is a type of isenthalpic process where a liquid or gas is cooled as it passes from a higher pressure state to a lower pressure state.

a.         a. Rankine Process

b.         b. Carnot Cycle

c.         c. Joule-Thomson process

d.         d. Refrigeration process

70.       Gasoline and Diesel Engines are best described by the

            .

a.         a. Otto Cycle

b.         b. Burnign Cycle

c.         c. Shikki Cycle

d.         d. Shapa R’ Elli Cycle

71.       Twenty grams of ice at 0?C melts to water at 0?C. How much does the entropy of the 20g change in this process?

a.         a. 30.5 J/K

b.         b. 24.6 J/K

c.         c. 21.3 J/K

d.         d. 15.7 J/K

72.       The first law of thermodynamics is based on which of the following principles?

a.         a. conservation of mass

b.         b. the enthalpy-entropy relationship

c.         c. action – reaction

d.         d. conservation of energy

73.       If a system absorbs 500 cal of heat at the same time does 400J of work, find the change in internal energy of the system.

a.         a. 1400 J

b.         b. 1700 J

c.         c. 1900 J

d.         d. 1500 J

74.       A gas is enclosed in a cylinder with a weighted piston as the top boundary. The gas is heated and expands from a volume of

0.04     m3 to 0.10 m3 at a constant pressure of 200 kPa. Find the work done on the system.

•          a. 5 kJ

•          b. 15 kJ

•          c. 10 kJ

•          d. 12 kJ

75.       A simple steam engine receives steam from the boiler at

 

a.         a. 11.28 %

b.         b. 36.77 %

c.         c. 20.36 %

d.         d. 17.66 %

76.       Heat which causes a change in temperature of a substance.

a.         a. Latent heat

b.         b. Sensible heat

c.         c. Specific heat

d.         d. Heat of Fusion

77.       Who coined the term latent heat?

a.         a. John Thompson

b.         b. Studey Baker

c.         c. Joe di Maggio

d.         d. Joseph Black

78.       Which of the following cannot be measured by a thermometer?

a.         a. Latent Heat

b.         b. Sensible Heat

c.         c. Specific Heat

d.         d. Heat of Fusion

79.       It is generally accepted as a law of nature that although one may closely approach 0 Kelvin it is impossible actually to reach it.

a.         a. First Law of thermodynamics

b.         b. Second Law of thermodynamics

c.         c. Third Law of thermodynamics

d.         d. Zeroth Law of thermodynamics

80.       One calorie is equal to           .

a.         a. 1/180 W.h

b.         b. 1/860 W.h

c.         c. 1/360 W.h

d.         d. 1/250 W.h

81.       A          is a reversible process in which there is transfer of heat and takes place according to the relation pVn = C where n is any constant.

a.         a. Polytropic process

b.         b. Entropy

c.         c. Ideal Gas Law

d.         d. Carnot Cycle

82.       The flow through an open system is   if all properties at each point within the system remain constant with respect to time.

a.         a. streamline flow

b.         b. steady flow

c.         c. constant flow

d.         d. algebraic flow

83.       The most efficient cycle that can operate between two constant temperature reservoir is the     .

a.         a. Otto Cycle

b.         b. Lazare Cycle

c.         c. Isothermal Cycle

d.         d. Carnot Cycle

84.       The flow energy of 150 L of a fluid passing a boundary to a system is 110 kJ. Determine the pressure at this point

a.         a. 733.33 kPa

b.         B. 8x10^5 kJ

c.         C. 1 x10^6 kJ

 

d.         b. 833.33 kPa

e.         c. 933.33 kPa

f.          d. 633.33 kPa

85.       Who is the father of thermodynamics?

a.         a. Lazare Carnot

b.         b. Sadi Carnot

c.         c. William Thompson

d.         d. Rudolf Classius

86.       If air is at pressure, p, of 3200 lbf/ft2, and at a temperature, T, of 800 ?R, what is the specific volume, v? (R=5303 ft-lbf/lbm-

?R, and air can be modeled as an ideal gas.)

a.         A.9.8 ft^3/lbm

b.         B.11.2 ft^3/lbm

c.         C.13.33 ft^3/lbm

d.         D.14.2 ft^3/lbm Formula: pv = RT v = RT / p

87.       Steam at 1000 lbf/ft^2 pressure and 300?R has specific volume of 6.5 ft^3/lbm and a specific enthalpy of 9800 lbf- ft/lbm. Find the internal energy per pound mass of steam.

a.         A.2500 lbf-ft/lbm

b.         B.3300 lbf-ft/lbm

c.         C.5400 lbf-ft/lbm

d.         D.6900 lbf-ft/lbm Formula: h= u+ pV u= h– pV

88.       3.0 lbm of air are contained at 25 psia and 100 ?F. Given that Rair = 53.35 ft-lbf/lbm- ?F, what is the volume of the container?

a.         A.10.7 ft^3

b.         B.14.7 ft^3

c.         C.15 ft^3

d.         D.24.9 ft^3

Formula: use the ideal gas law pV = mRT

T = (100 +460) ?R

V = mRT/p

89.       The compressibility factor, x, is used for predicting the behavior of non-ideal gases. How is the compressibility ty factor defined relative to an ideal gas? (subscript “c”refers to critical value)

a.         A. z = P / Pc

b.         B. z = pV/ RT

c.         C. z = T /Tc

d.         D. z = RT / pV

Hint: for an real gases the compressibility factor, x, is an dimensionless constant given by pV= zRT. Therefore z = pV / RT

90.       From the steam table, determine the average constant pressure specific heat (c) of steam at 10 kPa and45.8 ?C

a.         A.1.79 kJ/ kg-?C

b.         B.10.28 kJ/ kg-?C

c.         C.30.57 kJ/ kg-?C

d.         D. 100.1 kJ/ kg-?C Formula: ?h = c?T

From the steam table

At 47.7 ?C h= 2588.1 kJ/ kg At 43.8 ?C h= 2581.1 kJ/ kg

91.       A 10m^3 vessel initially contains 5 m^3 of liquid water and 5 m^3 of saturated water vapor at 100 kPa. Calculate the internal energy of the system using the steam table.

a.         A. 5 x10^5 Kj

b.         C. 3474.23 N

 

c.         D. 2 x10^6 kJ Formula: fromthe steamtable vƒ = 0.001043 m^3 / kg

vg = 1.6940 m^3 / kg

u ƒ= 417.3 kJ/kg ug= 2506kJ/kg formula: Mvap = V vap/vg

M liq = Vliq/ vƒ

u =uƒM liq + ug M vap

92.       A vessel with a volume of cubic meter contains liquid water and water vapor ion equilibrium at 600 kPa. The liquid water has mass of1kg. Using the steam table, calculate the mass of the water vapor.

a.         A. 0.99kg

b.         B. 1.57 kg

c.         C. 2.54 kg

d.         D. 3.16 kg

Formula: from the steam table at 600kPa vƒ = 0.001101 m^3 / kg

vg = 0.3157 m^3 / kg Vtot = mƒ vƒ + mg vg mg = (tot-mƒ vƒ) / vg

93.       Calculate the entropy of steam at 60psiawith a quality of 0.8

a.         A. 0.4274 BTU/lbm-?R

b.         B. 0.7303 BTU/lbm-?R

c.         C. 1.1577 BTU/lbm-?R

d.         D. 1.2172 BTU/lbm-?R Formula: fromthe steamtable at 60 psia:

sƒ = 0.4274 BTU/lbm-?R sƒg = 1.2172 BTU/lbm-?R)

s = sƒ + x sƒg where x = is the quality

94.       Find the change in internal energy of 5 lb. of oxygen gas when the temperature changes from 100 ?F to 120 ?F. CV = 0.157 BTU/lbm-?R

a.         A.14.7 BTU

b.         B.15.7 BTU

c.         C. 16.8 BTU

d.         D. 15.9 BTU

Formula: ?U= mcv?T

95.       Water (specific heat cv= 4.2 kJ/ kg ? K ) is being heated by a 1500 W h eater. What is the rate of change in temperature of 1kg of the water?

a.         A. 0.043 K/s

b.         B. 0.179 K/s

c.         C. 0.357 K/s

d.         D. 1.50 K/s Formula: Q = mcv (?T)

96.       A system weighing 2kN. Determine the force that accelerate if to 12 m/s^2.

a. vertically upward when g = 9.7 m/s^2

•          A. 4474.23 N

•          B.5484.23 N

•          C.4495.23 N

•          D.5488.23 N

Formula: F = m/k (a +g)

97.       Refer to problem # 11. Determine the force that accelerates if to 12 m/s^2. horizontally along frictionless plane.

a.         A. 2474.23 N

b.         B. 2574.23 N

c.         A. 8 kJ

d.         B. 10 kJ

 

e.         D. 2374.23 N

Formula :

M = wk / g F = ma /k

98.       A problem Drum ( 3 ft. diameter ; 6 ft. height ) is field with a fluid whose density is 50 lb/ft^3. Determine the total volume of the fluid.

a.         A. 42.41 ft^3

b.         B.44.35 ft^3

c.         C.45.63 ft^3

d.         D.41.23 ft^3 Formula: Vf = (pi d^2 h) / 4

99.       What is the resulting pressure when one pound of air at 15 psia and 200 ?F is heated at constant volume to 800 ?F?

a.         A.15 psia

b.         B. 28.6 psia

c.         C. 36.4 psia.

d.         D. 52.1 psia Formula :

T1/p1 = T2/p2 p2= p1T2 / T1

100.     What horse power is required to isothermally compress 800 ft^3 of Air per minute from 14.7 psia to 120 psia?

a.         A. 28 hp

b.         B.108 hp

c.         C.256 hp

d.         D.13900 hp Formula: W= p1V1 ln (p1/p2) Power = dW / dt