POWER ENGINEERING 2A2 EXAM UPDATED QUESTIONS AND
ANSWERS
Define a perfect gas - CORRECT ANSWER✅✅A perfect gas is a gas which is sufficiently removed from its
condensation temperature that it will remain in its gaseous state when subjected to changes of
temperature and pressure of the operation being considered.
The relationship between temperature, pressure and volume is consistent throughout a selected
working range. The behavior of a perfect gas can be used as a model for the behavior of real gases.
What are the units for gas law calculations? - CORRECT ANSWER✅✅The units must always be in
absolute pressure (not gauge pressure) and in degrees Kelvin.
What is the ideal gas law? - CORRECT ANSWER✅✅The ideal gas law represents the relationship among
pressure, volume and temperature that includes the mass of the substance.
PV=mRT
Dalton's Law - CORRECT ANSWER✅✅The total pressure of a mixture of gases is equal to the sum of the
individual (or partial) pressures which each gas would exert if the other gases were not present. In other
words, the partial pressure of each gas is calculated using the total volume, and the total pressure is the
sum of the partial pressures. (Ptotal=P1+P2+P3...)
What is the specific heat of a substance? - CORRECT ANSWER✅✅It is the amount of heat which is
required to raise a unit quantity through 1 Deg C rise in temperature.
A solid or a liquid has only one specific heat, where a gas has many, depending upon the conditions
under which the heat supply is given. The standard cases taken are heat addition at constant volume or
constant pressure.
Why is Cp always greater than Cv? - CORRECT ANSWER✅✅Assuming the same quantity of gas and the
same temperature rise in each case, the heat quantity supplied at a constant pressure must be greater
than that supplied under constant volume conditions because the in addition to raising the gas
temperature, work must be done on the piston to move it against the constant pressure.
,What type of information is provided by welding symbols? - CORRECT ANSWER✅✅-The type of weld or
welds required at the joint
-The exact location of the weld on the joint
-The size of the weld or welds
-The spacing of welds if more than one is used on a joint
-Special procedures or notes with respect to the weld
When it comes to welding, what are the basic joint types? - CORRECT ANSWER✅✅-Butt
-Lap
-Tee
-Corner
-Edge
When are groove welds used? - CORRECT ANSWER✅✅They are used when the surfaces being joined
are butted against each other in such a way that a groove is created.
What are some standard groove shapes? - CORRECT ANSWER✅✅-V
-Double V
-Bevel
-Square
-U
-Double U
-J
-Scarf (The joined edges are machined flat but at an angle, common for brazing)
-Flare-v
-Flare bevel
,Define the following terms: Weld root, root opening, weld depth, reinforcement and melt through -
CORRECT ANSWER✅✅Weld root - the bottom edge of a weld or the deepest point of a weld
Root opening - the space intentionally left between joined surfaces before welding.
Weld depth - the distance from the surface of the material to the root of the weld
Reinforcement - the specified height of the weld above the surface of the material
Melt through - the thickness of the weld, measured from the root of the weld to the material surface,
when the root extends beyond the surface. This is often intentional for reinforcing the weld.
What is a fillet weld? - CORRECT ANSWER✅✅A fillet weld is a weld of approximately triangular cross
section that two surfaces at approximately right angles.
What it a box weld and another term for it? - CORRECT ANSWER✅✅It is a continuous fillet weld, used
to weld a vertical post to a flat plate. It is also called an all-around weld.
What type of weld is used when the strength of the joint is not crucial or complete sealing of the joint is
not necessary? - CORRECT ANSWER✅✅Staggered intermittent fillet welds. In order to successfully
produce these welds, the welder must know the length of the individual welds and the pitch. The pitch is
the distance between the mid point of the adjacent welds. In many cases the intermittent welds are not
staggered, but directly across from each other, with identical length and pitch.
What is a plug or slot weld? - CORRECT ANSWER✅✅This involves joining two relatively flat pieces with
a series of small welds that are deposited into drilled plugs or machined slots into on piece. The piece
with the slots or plugs is usually relatively thin and the sides may be perpendicular or bevelled.
What are the three types of metallurgy? - CORRECT ANSWER✅✅-Exctractive
-Mechanical
-Physical
, What is extractive metallurgy? What are the different types? - CORRECT ANSWER✅✅The study of
extraction and purification of metal from their ores, which is conducted in several steps. Each step
increases the purity by removing unwanted impurities.
Pyrometallurgy - melting the ore in a furnace to release the metal.
Hydrometallurgy - dissolving the metal from the ore and recovering it as a powder.
Electrometallurgy - dissolving the metal from the ore with the use of electricity, plate the metal out of
solution.
What is mechanical metallurgy? - CORRECT ANSWER✅✅It is the study of the techniques and
mechanical forces that shape and make the finished forms of metal. This includes studying the effects of
stress, time and temperature.
What is physical metallurgy? - CORRECT ANSWER✅✅It is the study of the structure of metals.
Properties of metals are intimately related to their structures. Careful modification of the structure can
produce more desirable and useful properties in a metal.
Define metals - CORRECT ANSWER✅✅Metals are substances that good conductors of heat and
electricity. They are generally malleable and ductile. They occur naturally in ores in the form of chemical
compounds such as sulphides or oxides. With the exception of the noble metals, such as platinum and
gold, metallic materials tend to react chemically with the environment and revert to compound forms
(corrosion).
In most metals, what are the three basic arrangements can the atoms of a metal take? - CORRECT
ANSWER✅✅-Face-centered cubic (FCC) - Fourteen atoms form the FCC unit cell. High ductility, low
shear and low tensile strength but good thermal and electrical conductivity. Gold, aluminum, silver,
lead, nickel, and gamma iron (between 910 and 1390 DegC)
-Body-centered cubic (BCC) - Nine atoms are contained in the BCC structure. High strength, low ductility,
and are very resistant to shear deformities. Chromium, tungsten, molybdenum, vanadium, alpha iron
(below 910 DegC), and delta iron (above 1390 DegC)
ANSWERS
Define a perfect gas - CORRECT ANSWER✅✅A perfect gas is a gas which is sufficiently removed from its
condensation temperature that it will remain in its gaseous state when subjected to changes of
temperature and pressure of the operation being considered.
The relationship between temperature, pressure and volume is consistent throughout a selected
working range. The behavior of a perfect gas can be used as a model for the behavior of real gases.
What are the units for gas law calculations? - CORRECT ANSWER✅✅The units must always be in
absolute pressure (not gauge pressure) and in degrees Kelvin.
What is the ideal gas law? - CORRECT ANSWER✅✅The ideal gas law represents the relationship among
pressure, volume and temperature that includes the mass of the substance.
PV=mRT
Dalton's Law - CORRECT ANSWER✅✅The total pressure of a mixture of gases is equal to the sum of the
individual (or partial) pressures which each gas would exert if the other gases were not present. In other
words, the partial pressure of each gas is calculated using the total volume, and the total pressure is the
sum of the partial pressures. (Ptotal=P1+P2+P3...)
What is the specific heat of a substance? - CORRECT ANSWER✅✅It is the amount of heat which is
required to raise a unit quantity through 1 Deg C rise in temperature.
A solid or a liquid has only one specific heat, where a gas has many, depending upon the conditions
under which the heat supply is given. The standard cases taken are heat addition at constant volume or
constant pressure.
Why is Cp always greater than Cv? - CORRECT ANSWER✅✅Assuming the same quantity of gas and the
same temperature rise in each case, the heat quantity supplied at a constant pressure must be greater
than that supplied under constant volume conditions because the in addition to raising the gas
temperature, work must be done on the piston to move it against the constant pressure.
,What type of information is provided by welding symbols? - CORRECT ANSWER✅✅-The type of weld or
welds required at the joint
-The exact location of the weld on the joint
-The size of the weld or welds
-The spacing of welds if more than one is used on a joint
-Special procedures or notes with respect to the weld
When it comes to welding, what are the basic joint types? - CORRECT ANSWER✅✅-Butt
-Lap
-Tee
-Corner
-Edge
When are groove welds used? - CORRECT ANSWER✅✅They are used when the surfaces being joined
are butted against each other in such a way that a groove is created.
What are some standard groove shapes? - CORRECT ANSWER✅✅-V
-Double V
-Bevel
-Square
-U
-Double U
-J
-Scarf (The joined edges are machined flat but at an angle, common for brazing)
-Flare-v
-Flare bevel
,Define the following terms: Weld root, root opening, weld depth, reinforcement and melt through -
CORRECT ANSWER✅✅Weld root - the bottom edge of a weld or the deepest point of a weld
Root opening - the space intentionally left between joined surfaces before welding.
Weld depth - the distance from the surface of the material to the root of the weld
Reinforcement - the specified height of the weld above the surface of the material
Melt through - the thickness of the weld, measured from the root of the weld to the material surface,
when the root extends beyond the surface. This is often intentional for reinforcing the weld.
What is a fillet weld? - CORRECT ANSWER✅✅A fillet weld is a weld of approximately triangular cross
section that two surfaces at approximately right angles.
What it a box weld and another term for it? - CORRECT ANSWER✅✅It is a continuous fillet weld, used
to weld a vertical post to a flat plate. It is also called an all-around weld.
What type of weld is used when the strength of the joint is not crucial or complete sealing of the joint is
not necessary? - CORRECT ANSWER✅✅Staggered intermittent fillet welds. In order to successfully
produce these welds, the welder must know the length of the individual welds and the pitch. The pitch is
the distance between the mid point of the adjacent welds. In many cases the intermittent welds are not
staggered, but directly across from each other, with identical length and pitch.
What is a plug or slot weld? - CORRECT ANSWER✅✅This involves joining two relatively flat pieces with
a series of small welds that are deposited into drilled plugs or machined slots into on piece. The piece
with the slots or plugs is usually relatively thin and the sides may be perpendicular or bevelled.
What are the three types of metallurgy? - CORRECT ANSWER✅✅-Exctractive
-Mechanical
-Physical
, What is extractive metallurgy? What are the different types? - CORRECT ANSWER✅✅The study of
extraction and purification of metal from their ores, which is conducted in several steps. Each step
increases the purity by removing unwanted impurities.
Pyrometallurgy - melting the ore in a furnace to release the metal.
Hydrometallurgy - dissolving the metal from the ore and recovering it as a powder.
Electrometallurgy - dissolving the metal from the ore with the use of electricity, plate the metal out of
solution.
What is mechanical metallurgy? - CORRECT ANSWER✅✅It is the study of the techniques and
mechanical forces that shape and make the finished forms of metal. This includes studying the effects of
stress, time and temperature.
What is physical metallurgy? - CORRECT ANSWER✅✅It is the study of the structure of metals.
Properties of metals are intimately related to their structures. Careful modification of the structure can
produce more desirable and useful properties in a metal.
Define metals - CORRECT ANSWER✅✅Metals are substances that good conductors of heat and
electricity. They are generally malleable and ductile. They occur naturally in ores in the form of chemical
compounds such as sulphides or oxides. With the exception of the noble metals, such as platinum and
gold, metallic materials tend to react chemically with the environment and revert to compound forms
(corrosion).
In most metals, what are the three basic arrangements can the atoms of a metal take? - CORRECT
ANSWER✅✅-Face-centered cubic (FCC) - Fourteen atoms form the FCC unit cell. High ductility, low
shear and low tensile strength but good thermal and electrical conductivity. Gold, aluminum, silver,
lead, nickel, and gamma iron (between 910 and 1390 DegC)
-Body-centered cubic (BCC) - Nine atoms are contained in the BCC structure. High strength, low ductility,
and are very resistant to shear deformities. Chromium, tungsten, molybdenum, vanadium, alpha iron
(below 910 DegC), and delta iron (above 1390 DegC)
