Book 2 Flashcards
If a substance goes through a process that changes its composition so that it is no longer the same substance, then the substance has undergone a:
a. Physical change
b.Heterogeneous change
c. Homogeneous change
d.Chemical change
e.Mechanical change
Chemical change
When is hot oil an ideal heat transfer fluid?
a. when high temperature, high pressure process fluids are needed
b. when glycol is too expensive
c.when low temperature process fluids are needed at high pressure
d.when high temperature process fluids are needed at low pressure
when high temperature process fluids are needed at low pressure
An intensive physical property is one that is:
a.Dependent on the amount of matter
b.Independent of the amount of matter
c.Dependent on the volume
d.Dependent on the density of a substance
e.Dependent on the amount of pressure applied
Independent of the amount of matter
Calculate the boiler efficiency if the heat supplied to the steam is 26 880 kJ per kg of fuel burned and the heating value of 1 kg of fuel is 32 000 kJ.
a.72%
b.78%
c.84%
d.87.7%
e.89.35%
84%
Calculate the heat required to convert 100 kg of water at 35°C into dry saturated steam at a pressure of 1500 kPa (abs).
a.2784.8 kJ
b.5563.4 kJ
c.2781.7 kJ
d.184.09 kJ
e.1.1330 kJ
5563.4 kJ
What is the total enthalpy of 2 kg of dry saturated steam at 1100 kPa abs?
a.2784.8 kJ
b.5563.4 kJ
c.2781.7 kJ
d.184.09 kJ
e.1.1330 kJ
5563.4 kJ
An example of a physical change in matter is the
a.Reaction of sodium with chlorine
b. Boiling of a refrigerant
c.Burning of coal
d.Rusting of steel
e.Corrosion of boiler metal
Boiling of a refrigerant
When the temperature of an object is increased, its change in length is proportional to its:
a.Initial length and initial temperature.
b.Cross-sectional area and temperature.
c.Volume and temperature increase.
d.Initial length and temperature increase
e.Initial temperature, but inversely proportional to its length
Initial length and temperature increase.
If 2460 kJ/kg of heat is added to water at 0°C to produce wet steam at 1500 kPa abs, calculate the dryness fraction.
a.74%
b.64%
c.91%
d.78%
e.83%
83%
How many kJ of heat will be required to convert 65 kg of water at 15°C into saturated steam at 650 kPa abs ?
a.
2697.31
b.
2760.3
c.
62.99
d.
282 329.29
e.
175 325
175 325
Which equation is perfectly balanced?
a.
C2H5OH + 3 O2 → 2 CO2 + 3 H2O
b.
C2H5OH + 4 O2 → 2 CO2 + 3 H2O
c.
C2H5OH + O2 → 2 CO2 + H2O
d.
C2H5OH + O2 → 1 CO2 + H2O
C2H5OH + 3 O2 → 2 CO2 + 3 H2O
An example of a homogenous mixture of solids is:
Select one:
a.
Metal alloy
b.
Soil
c.
Concrete
d.
Plastic
e.
Wood
Metal alloy
When heat flows from molecule to molecule within a substance, or between bodies that are in direct contact, the method of heat transfer is called:
a.
Convection
b.
Induction
c.
Conduction
d.
Contraction
e.
Radiation
Conduction
The amount of heat absorbed by water when it evaporates at atmospheric pressure is
Select one:
a.
99.63 kJ/kg
b.
335 kJ/kg
c.
417.46 kJ/kg
d.
2257 kJ/kg
e.
2675.5 kJ/kg
2257 kJ/kg
Condensation losses in steam can be avoided by:
Select one:
a.
Heating the steam to saturation temperature
b.
Using wet steam
c.
Using only high pressure steam
d.
Installing steam separators
e.
Using superheated steam
Using superheated steam
Which of the following statements is TRUE?
Select one:
a.
In general, coefficients of expansion of solids are greater than those of liquids.
b.
Liquids do not contract when cooled.
c.
The Coefficient of Expansion for a liquid changes if the liquid temperature changes
d.
Solids contract when heated.
e.
Water will only expand when its temperature is increased.
The Coefficient of Expansion for a liquid changes if the liquid temperature changes
What does 1 kilojoule (kJ) equal?
a.
1000 kJ or 103 kJ
b.
1000 J or 103 J
c.
1000 J or 103 kJ
d.
1000 J or 103 J
1000 J or 103 J
Steam containing water particles in suspension is defined as:
Select one:
a.
Dry steam
b.
Theoretical steam
c.
Wet steam
d.
Sub-cooled steam
e.
Superheated steam
Wet steam
Natural convection is a method of heat transfer in which the movement of the fluids is due solely to the:
a.
Surface pressure.
b.
Difference in densities.
c.
Action of a pump or fan.
d.
Gravitational differences.
e.
Activity of the radiant heat
Difference in densities.
In a covalent bond, the valence electrons are ____________ between the atoms.
a.
Repelled
b.
Absent
c.
Loaned
d.
Shared
Shared
Heat that brings about a change of state:
Select one:
a.
Can be sensed by a thermometer
b.
Is called sensible heat
c.
Causes a change of temperature
d.
Is called latent heat
e.
Is called specific heat
Is called latent heat
Large areas, such as warehouses, are usually heated by:
Select one:
a.
Unit heaters
b.
Radiators
c.
Convectors
d.
Open heaters
e.
Space heaters
Unit heaters
A substance that cannot be decomposed into other substances by chemical means is:
Select one:
a.
a Mixture
b.
a Compound
c.
a Solution
d.
an Atom
e.
an Element
an Element
How much heat is in 20 kg of 80% dry steam at 2250 kPa abs?
Select one:
a.
48 573 kJ
b.
55 653 kJ
c.
2781.7 kJ
d.
33,241 kJ
e.
1.1335 MJ
48 573 kJ
Calculate the sensible heat required to raise the temperature of 10 kg of boiler feedwater from 20°C to the boiling point at 300 kPa.
a.
2725.30 kJ
b.
26 413.4 kJ
c.
28 092.6 kJ
d.
2641.34 kJ
26 413.4 kJ
Which of the following statements is true?
Select one:
a.
If there is a temperature difference between a heat source and a cooler object in contact with the source, heat will be transferred to the cooler object.
b.
Heat can be transferred from cold bodies to hot bodies without using an external supply of work.
c.
Specific heat is the same for every substance.
d.
Specific heat capacity is the same for every state of matter of the same substance.
e.
1 J is less than 1 Nm of work.
If there is a temperature difference between a heat source and a cooler object in contact with the source, heat will be transferred to the cooler object.
Radiant heat:
Select one:
a.
Travels in straight lines.
b.
Is present in oil firing but not fuel gas firing.
c.
Radiates through the superheater tube walls.
d.
Radiates through the water in the water walls.
e.
Requires a transfer medium.
Travels in straight lines.
The First Law of Thermodynamics states that heat and work
Select one:
a.
Cannot co-exist
b.
Are mutually convertible
c.
Are unrelated
d.
Are identical
e.
Produce friction
Are mutually convertible
The transfer of heat involving the movement of a fluid is defined as:
Select one:
a.
Conduction
b.
Convection
c.
Radiation
d.
Flux
e.
Thermo-circulation
Convection
The Second Law of Thermodynamics states that, unaided, heat will only flow from a:
Select one:
a.
Cold substance to a hotter substance.
b.
Warm substance to a hotter substance.
c.
Hot substance to a hotter substance.
d.
Region of low heat
e.
Higher temperature body to a lower temperature body.
Higher temperature body to a lower temperature body.
The temperature at which all molecular motion is said to completely cease is:
Select one:
a.
-373°C
b.
0°C
c.
0°F
d.
-460°R
e.
0 K
0 K
25.4 kg of copper at 33°C receives 240 kJ of heat. Calculate the final temperature of the metal.
Select one:
a.
55.454°C
b.
57.353°C
c.
58.353°C
d.
59.756°C
e.
61.243°C
57.353°C
In the First Law of Thermodynamics, heat supplied = increase in internal energy + ____________:
Select one:
a.
Energy supplied.
b.
Energy absorbed.
c.
Work input.
d.
Work done.
e.
Power output.
Work done.
In the Steam Tables, Hg equals:
Select one:
a.
Hf - Hfg
b.
Hf + Hfg
c.
Hf x Hfg
d.
Hf / Hfg
e.
Hf2 + Hfg2
Hf + Hfg
Calculate the heat to be supplied per kilogram of water to produce 80% dry steam at 250 kPa.
a.
1745.2 kJ/kg
b.
17 452 kJ/kg
c.
2173.52 kJ/kg
d.
2726.875 kJ/kg
1745.2 kJ/kg
The information found in Column 8 (labeled Hf)of Table 1 of the Steam Tables is the:
Select one:
a.
Sensible heat
b.
Latent heat
c.
Specific heat
d.
Latent heat of fusion
e.
Latent heat of evaporation
Sensible heat
The second law of thermodynamics states that heat will flow only from a hot substance to what kind of substance?
a.
Warmer
b.
Colder
c.
Exothermic
d.
Endothermic
Colder
Columns 8, 9 and 10 of Table 1 of the Steam Tables, deal with
Select one:
a.
Internal energy
b.
Enthalpy
c.
Entropy
d.
Specific volume
e.
Potential energy
Enthalpy
The total enthalpy of 11 kg of steam at 950 kPa abs is 24 528.713 kJ. Determine the dryness of the steam.
Select one:
a.
0.54
b.
0.64
c.
0.68
d.
0.73
e.
0.87
0.73
What quantity of heat is required to raise the temperature of 2 kgs of copper from 10°C to 60°C if the specific heat of copper is 0.388 kJ/kg°C.
a.
38.8 kJ
b.
38 800 kJ
c.
19.4 J
d.
19.4 kJ
38.8 kJ
Superheated steam:
Select one:
a.
Is produced in the saturated steam drum
b.
Temperature is higher than the saturation temperature
c.
Is almost dry and contains very little moisture
d.
Cannot be used for soot blowers
e.
Can only exist at pressures above 103 kPag
Temperature is higher than the saturation temperature
Any material made up of distinct elements, compounds, or both, that are not chemically combined with one another, is a:
Select one:
a.
Solid
b.
Mixture
c.
Molecule
d.
Crystal
e.
Compound
Mixture
________ heat causes a change in the temperature of a substance without changing its state.
Select one:
a.
Sensible
b.
Latent
c.
Super
d.
Specific
e.
Saturated
Sensible
Which equation states the first law of thermodynamics as it applies to a closed system?
a.
Net work = Net temp
b.
Net work = Net heat
c.
Change in work = Change in temp
d.
Change in work = Change in heat
Change in work = Change in heat
In the Steam Tables, the numbers given for the specific volume of steam are in what units?
Select one:
a.
cubic centimeters
b.
cubic centimeters per gram
c.
cubic meters per kilogram
d.
kilograms per cubic meter
e.
grams per cubic centimeter
cubic centimeters per gram
An example of a two-phase heat transfer fluid is
Select one:
a.
steam
b.
heat transfer oil
c.
glycol/water
d.
air
steam
An example of a heterogeneous mixture is:
Select one:
a.
Sand and water
b.
Soda water
c.
Acid
d.
Flue gas
e.
Stainless steel
Sand and water
What type of exchanger is a U-tube heat exchanger?
a.
Plate heat
b.
Shell and coil heat
c.
Shell and tube
d.
Bare tube
Shell and tube
An example of a two-phase heat transfer fluid is
Select one:
a.
petroleum
b.
heat transfer oil
c.
anhydrous ammonia
d.
glycol/water
anhydrous ammonia
What is an example of an antifreeze fluid?
a.
Steam
b.
Anhydrous ammonia
c.
Air/water mixture
d.
Ethylene glycol
Ethylene glycol
The state of matter of a particular substance is dependent on its:
Select one:
a.
Size and shape
b.
Temperature and pressure
c.
Weight and length
d.
Inertia and internal energy
e.
Pressure and density
Temperature and pressure
How do you handle condensate during start-up?
a.
Open trap inlet valve
b.
Open trap outlet valve
c.
Close trap bypass valve
d.
Open trap bypass
Open trap bypass
A cylindrical tank 0.5 m in diameter and 4 m long is filled with water at 15°C. Find the quantity of heat required to raise the water to 71°C. (Use specific heat of water = 4.2 kJ/kg/°C.)
Select one:
a.
120 000 kJ
b.
150 000 kJ
c.
165 000 kJ
d.
178 527 kJ
e.
184 726 kJ
184 726 kJ
How much heat must be supplied to 200 kg of water at 20°C to make steam at 850 kPa abs and 87% dry?
Select one:
a.
2039.4 kJ
b.
407 880 kJ
c.
1774.28 kJ
d.
424 627.98 kJ
e.
484 507.6 kJ
484 507.6 kJ
What term refers to a liquid’s resistance to sheer forces?
a.
Boiling point
b.
Viscosity
c.
Thermal capacity
d.
Freezing point
Viscosity
Which of the following is a limiting factor for the fin spacing of an HVAC coil
Select one:
a.
Temperature of steam in coils
b.
Temperature of chilled water in the coils
c.
Fin material
d.
Resistance to airflow
e.
Face velocity
Resistance to airflow
_____ refers to the transfer of heat via electromagnetic waves.
Select one:
a.
Convection
b.
Transmission
c.
Conduction
d.
Induction
e.
Radiation
Radiation
How does the hydroxide ion (OH–) become more stable?
a.
If it gains an electron as it is reduced
b.
If it gains an electron as it is oxidized
c.
If it loses an electron as it is oxidized
d.
If it loses an electron as it is reduced
If it loses an electron as it is oxidized
Saturated steam:
Select one:
a.
Is steam that is saturated with moisture
b.
Is steam at saturation temperature
c.
Is steam that is neither wet nor dry
d.
Contains more than 50% moisture
e.
Flows from a boiler’s superheater outlet
Is steam at saturation temperature
According to ASME BPVC Section VII, heat exchangers and similar vessels shall be protected with a .
Select one:
a.
low temperature cut-off device
b.
high temperature cut-off device
c.
pressure relief device
d.
high pressure cut-off device
pressure relief device
A simple machine is required to raise 1 tonne of stones a vertical distance of 30m. If the efficiency of the pulley is 100%, how much work must be done on the pulley to raise the stone?
Select one:
a.
294.3 J
b.
30 kJ
c.
35 kJ
d.
294.27 kJ
294.27 kJ
With static or kinetic friction, the force of friction is proportional to the _______ that presses the two surfaces together.
Select one:
a.
Pressure
b.
Mass
c.
Force
d.
Energy
Force
When a body falls from a height, what is its potential energy converted to?
a.
Kinetic energy
b.
Friction
c.
Power
d.
Watts
Kinetic energy
A train starts off from rest and reaches a velocity of 100km/h in 8 minutes. If the velocity increases uniformly, how far will the train travel during the first 8 minutes?
Select one:
a.
6.67 km
b.
7.43 km
c.
8.50 km
d.
9.25 km
6.67 km
A uniformly applied force, acting at right angles to a surface, divided by the surface area, is defined as:
Select one:
a.
Acceleration
b.
Pressure
c.
Weight
d.
Surface area
Pressure
What is the force of gravity exerted on an object that has a mass of 5.2 tonnes?
a.
5.10 N
b.
5101.2 N
c.
51 012 N
d.
51.01 N
51 012 N
If a force of 1400 N, applied in the direction of movement, will cause continued steady movement of a 400 kg crate. Calculate the coefficient of kinetic friction.
Select one:
a.
3.6
b.
5.6
c.
0.56
d.
0.36
0.36
A mass of 400 kg is moved a horizontal distance of 30 m due to a force of 300 kN. What is the amount of work done?
a.
9000 J
b.
12 000 kJ
c.
12 000 J
d.
9000 kJ
9000 kJ
When a body with a mass of 250 kg is moved upward a distance of 15 m in 11 s, how much power is developed?
a.
3750 J/s
b.
2646 J/s
c.
3344 J/s
d.
36 790 J/s
3344 J/s
A car has an initial velocity of 25km/h and in 84 seconds it accelerates to 110km/h. How far did it travel while accelerating?
Select one:
a.
2575 m
b.
1575 m
c.
757 m
d.
575 m
1575 m
A block and tackle system has 3 pulleys in each of two blocks. If a downward effort of 100 N is applied and the machine has an efficiency of 83.6%, what is the maximum mass that can be lifted?
Select one:
a.
501.6 kg
b.
51.1 kg
c.
5113.1 kg
d.
250 kg
51.1 kg
Velocity may be defined as:
Select one:
a.
Speed
b.
Linear speed
c.
Speed in a given direction
d.
Speed in a given time
Speed in a given direction
A 4 m long exchanger tube shortens by 4 mm under compressive load. What is the strain?
a.
1.0
b.
0.001
c.
0.0001
d.
0.01
0.001
A hole 3 cm in diameter is to be punched out of a steel plate that is 8 cm thick. The shear stress of the material is 670 GPa. What force is required on the punch?
Select one:
a.
4 735 509 GN
b.
5051.6 MN
c.
1.6 x 1013 N
d.
9036 MN
5051.6 MN
A large gear with 50 teeth interacts with a smaller gear with 15 teeth. If the larger gear rotates at 100 rev/min, determine a) the gear ratio, and b) the speed of the smaller gear.
a.
a) 0.3, b) 333.33
b.
a) 3.33, b) 333.33
c.
a) 0.3, b) 30
d.
a) 3.33, b) 30
a) 3.33, b) 333.33
The ratio between the ultimate strength and the allowable stress is called the:
Select one:
a.
Ultimate stress
b.
Maximum allowable load
c.
Working stress
d.
Safety factor
Safety factor
A force of 320kN acts perpendicular to a lever arm, at a distance of 4m from a point. What turning moment does the force produce about the point?
Select one:
a.
80 kNm
b.
1280 kNm
c.
1280 kN
d.
1280 Watts
1280 kNm
How is acceleration defined?
a.
Change of velocity ÷ time taken to change
b.
Time taken to change ÷ velocity
c.
Velocity ÷ acceleration
d.
Acceleration ÷ velocity
: Change of velocity ÷ time taken to change
A body moves from Point A to Point B in a semicircular path. If the radius of the semicircle is 2 m, calculate the displacement from Point A to Point B.
Select one:
a.
2 m
b.
4 m
c.
6 m
d.
8 m
4 m
Shear stress is caused by forces from which direction?
a.
Inclined to the surface
b.
At least two directions
c.
Parallel to the surface
d.
Perpendicular to the surface
Parallel to the surface
Which of the following statements about belt drive systems is FALSE?
Select one:
a.
Linear speed on a point of each pulley will be the same as the linear speed of the belt.
b.
Tension in the bottom belt is always double that in the top belt.
c.
Belt driver pulleys move follower pulleys by means of frictional force between the belt and the pulleys.
d.
Rotational speed will be equal if the pulley diameters are equal.
Tension in the bottom belt is always double that in the top belt.
What is the power required to apply a 200kN force over a distance of 15m in 15 seconds?
Select one:
a.
3000 W
b.
1500 kW
c.
1000 kW
d.
200 kW
200 kW
Calculate the strain if a body’s original length is 20 cm and the length after stretching is 20.4 cm.
a.
0.002
b.
0.2
c.
2
d.
0.02
0.02
A 28-tooth gear turns at 100 rpm and drives a 112-tooth gear. What is the speed of the follower gear?
Select one:
a.
400 rpm
b.
25 rpm
c.
31.36 rpm
d.
125.44 rpm
25 rpm
The area under a velocity vs. time graph equals:
Select one:
a.
Distance
b.
Speed
c.
Acceleration
d.
Displacement
Displacement
A rock is dropped from a bridge and hits the water 4.2 s later. How high is the bridge above the water?
a.
92 m
b.
41.2 m
c.
86.5 m
d.
106 m
41.2 m
A lever is used to move a load of 2000 N by applying an effort of 100 N. What is the mechanical advantage of the lever?
a.
2
b.
200
c.
20
d.
2000
20
What system does a space diagram illustrate?
a.
System of vectors
b.
System of scalars
c.
Vector diagram
d.
Scalar diagram
System of vectors
A wheel and axle has a mechanical advantage of 10. Calculate the diameter of the axle if the diameter of the wheel is 30cm.
Select one:
a.
3 cm
b.
3.3 cm
c.
6 cm
d.
15 cm
3 cm
An object is dropped from a height of 45m. What will be its velocity immediately before it hits the ground?
Select one:
a.
882.9 m/s
b.
441.5 m/s
c.
22.50 m/s
d.
29.71 m/s
29.71 m/s
A pump is required to raise 600 litres of fresh water a vertical distance of 120m. If the efficiency of the pump is 45%, how much work must be done on the pump to raise the water?
Select one:
a.
1570 GJ
b.
1570 MJ
c.
1570 kJ
d.
1570 J
1570 kJ
The ratio of the load to the effort in a simple machine is called the:
Select one:
a.
Velocity ratio
b.
Actual mechanical advantage
c.
Efficiency
d.
Power
Actual mechanical advantage
An object is thrown directly downwards from a height of 60 m with an initial velocity of 11 m/s. What will be its velocity on impact with the ground?
Select one:
a.
34.5 m/s
b.
36.03 m/s
c.
24.2 m/s
d.
126.38 m/s
36.03 m/s
A body moves in a straight line at 20m/s. Six seconds later it is moving at 35m/s. What was the acceleration of the body during that time?
Select one:
1.
9.167 m/s²
2.
9.167 m/s
3.
0.4 m/s²
4.
2.5 m/s²
2.5 m/s²
Calculate the work done to raise a 3000 kg boiler a distance of 60 m.
a.
1.77 MJ
b.
177 kJ
c.
1.77 kJ
d.
17.7 MJ
1.77 MJ
A 68.5kg object is at rest at a height of 65m above the earth’s surface. What is its kinetic energy?
Select one:
a.
4.45 kJ
b.
4.37 kJ
c.
34.25 kJ
d.
0 kJ
0 kJ
The rate of doing work is called _________.
Select one:
a.
Power
b.
Kinetic energy
c.
Potential energy
d.
Work
Power
Find the force required to start a 1 tonne object moving along a surface with a coefficient of friction of 0.62.
Select one:
a.
620 N
b.
6.1 N
c.
9810 N
d.
6082.2 N
6082.2 N
A simple machine is one that receives energy by means of a single applied force and produces work by means of:
Select one:
a.
Multiple output forces
b.
An energy form
c.
Distance moved
d.
A single output force
A single output force
If a force of 2400 N acts on the bottom of a tank that measures 4 m × 4 m, what is the pressure?
a.
1.5 kPa
b.
150 Pa
c.
15 kPa
d.
150 J
150 Pa
