4th Class Power Engineering Part A
Exam Questions With Correct Marking
Scheme
/.Velocity (m/s) - Answer-✅Change in position / time
/.Acceleration (m/s^2) - Answer-✅Change in velocity (m/s) / time (s)
/.Force (Newton) - Answer-✅mass (kg) x acceleration (m/s^2) , any action on a body
that tends to change its size, shape, or its state of rest or motion
/.Force of Gravity - Answer-✅mass (kg) x 9.81 m/s^2
/.Pressure (Pa) - Answer-✅Force (N) / area (m^2)
/.Work (J) - Answer-✅Force (N) x distance (m)
/.Power - Answer-✅Work done / time , Rate of doing work
/.Potential Energy (J) - Answer-✅mass x gravity x height , the ability of a body to do
work due by virtue of its position
/.Kinetic Energy (J) - Answer-✅1/2 x mass x velocity^2 , The ability of a body to do work
due to its motion
/.Energy (J) - Answer-✅The capacity of a body to do work
/.Tonne - Answer-✅1000 kilograms
/.Moment of Force (Nm) - Answer-✅Force (N) x Distance (m) , A force, acting on a
body at any distance from a point on that body, will tend to produce rotation around that
point
/.Clockwise Moments - Answer-✅Equal to Counter-clockwise moments
/.Upward Forces - Answer-✅Equal to Downward forces
,/.Actual Mechanical Advantage (Ma) - Answer-✅Load (N) / Effort (N)
/.Velocity Ratio (VR) - Answer-✅Distance moved by Effort / Distance moved by Load
/.Efficiency - Answer-✅Output Work / Input Work
/.Output Work - Answer-✅Load x Distance moved by load
/.Input Work - Answer-✅Effort x Distance moved by effort , Equals Output work +
Wasted work
/.Ideal Mechanical Advantage (MA) - Answer-✅Equal to Velocity Ratio (VR)
/.Load x r - Answer-✅Equal to Effort x R
/.VR - Answer-✅Equal to R/r and D/d
/.Load /Effort - Answer-✅Equal to R/r
/.Scalar - Answer-✅A physical quantity that has magnitude but no direction
/.Vector - Answer-✅A quantity that has magnitude and direction
/.Space Diagram - Answer-✅Illustrates a system of vectors
/.Co-planar Vectors - Answer-✅Vectors that are all in the same plane
/.Concurrent Vectors - Answer-✅Vectors whose lines of action meet at one point
/.Resultant - Answer-✅A vector that represents the sum of two or more vectors
/.Absolute Pressure - Answer-✅Atmospheric pressure + gauge pressure
/.Static Friction - Answer-✅A friction force that acts on objects that are not moving.
Always greater than kinetic friction
/.Kinetic Friction - Answer-✅Friction that opposes motion once the motion has already
started. Not affected by speed of body Always greater than rolling friction.
/.Rolling Friction - Answer-✅The friction force that acts on rolling objects, Always less
than kinetic friction
,/.Fluid Friction - Answer-✅Friction that occurs as an object moves through a fluid
/.Force of Friction - Answer-✅Force that resists motion when two materials are in
contact. Proportional to the force that presses the two surfaces together. Not affected by
area. Affected by roughness.
/.Elasticity - Answer-✅The ability of a material to return to its original shape after being
disturbed
/.Stiffness - Answer-✅Ability of a material to resist a change in shape or size when a
load is applied
/.Plasticity - Answer-✅Ability of a material to retain its deformed shape when a
deforming force is removed
/.Ductility - Answer-✅Ability of a material to be stretched and reduced in cross section
without breaking
/.Toughness - Answer-✅Ability of a material to absorb energy before breaking
/.Hardness - Answer-✅Ability of a material to resist penetration
/.Stress - Answer-✅Internal resistance to an external load , Equal to Load (N) / Area
(m^2)
/.Tensile Stress - Answer-✅Forces that act at opposite ends of a bar and pull away
from each other, creating tension on the bar
/.Compressive Stress - Answer-✅A stress due to a force pushing together on a body
/.Shear Stress - Answer-✅Forces on a bar that act parallel to another but are not on the
same plane
/.Ultimate Stress - Answer-✅The stress at which fracture of the material occurs
/.Allowable Stress - Answer-✅The greatest stress which a material is capable of
developing without permanent deformation remaining upon the complete release of
stress.
/.Elastic Limit - Answer-✅Maximum stress that a material will withstand without
permanent deformation. Will return to its original size and shape
/.Factor of Safety - Answer-✅Ultimate Stress / Allowable Stress
, /.Strain - Answer-✅A measure of the deformation produced in a member by a load ,
Equal to Change in Length (l) / Original Length (L)
/.Circumferance - Answer-✅pi x Diameter
/.Linear Speed - Answer-✅Equal to rev/min x pi D / 60
/.Four States of Matter - Answer-✅solid, liquid, gas, plasma
/.Phase - Answer-✅One individual substance in one particular state
/.Chemical Properties - Answer-✅Only observed when there is a chemical change or
reaction , Examples are Heat of combustion, Toxicity, Flammability, Chemical Stability
/.Physical Properties - Answer-✅Characteristics that you can observe without a change
in the composition of matter
/.Intensive Physical Property - Answer-✅Not dependent on the amount of matter
/.Extensive Physical Property - Answer-✅Dependent on the amount of matter
/.Mixture - Answer-✅A combination of two or more substances that are not chemically
combined
/.Homogeneous Mixture - Answer-✅AKA Solution , Only has one set of properties ,
Possible only when all the components are in the same physical state , Ex. Flue gas
/.Heterogenous Mixture - Answer-✅Non-uniform Composition , Substances may or may
not be in the same physical state , Ex. Oil and water emulsion , Sand and water
/.Matter - Answer-✅Can be described in terms of its states, physical, and chemical
properties , State of matter is dependent on its temperature and pressure
/.Pure Substances - Answer-✅Elements and Compounds
/.Atomic Number - Answer-✅Represents the number of protons in an atom
/.First Law of Thermodynamics - Answer-✅The increase in internal energy of a closed
system is equal to the heat supplied to the system minus work done by it (change in
work=change in heat)
/.Second Law of Thermodynamics - Answer-✅Unaided, heat will flow only from a hot
substance to a colder substance
Exam Questions With Correct Marking
Scheme
/.Velocity (m/s) - Answer-✅Change in position / time
/.Acceleration (m/s^2) - Answer-✅Change in velocity (m/s) / time (s)
/.Force (Newton) - Answer-✅mass (kg) x acceleration (m/s^2) , any action on a body
that tends to change its size, shape, or its state of rest or motion
/.Force of Gravity - Answer-✅mass (kg) x 9.81 m/s^2
/.Pressure (Pa) - Answer-✅Force (N) / area (m^2)
/.Work (J) - Answer-✅Force (N) x distance (m)
/.Power - Answer-✅Work done / time , Rate of doing work
/.Potential Energy (J) - Answer-✅mass x gravity x height , the ability of a body to do
work due by virtue of its position
/.Kinetic Energy (J) - Answer-✅1/2 x mass x velocity^2 , The ability of a body to do work
due to its motion
/.Energy (J) - Answer-✅The capacity of a body to do work
/.Tonne - Answer-✅1000 kilograms
/.Moment of Force (Nm) - Answer-✅Force (N) x Distance (m) , A force, acting on a
body at any distance from a point on that body, will tend to produce rotation around that
point
/.Clockwise Moments - Answer-✅Equal to Counter-clockwise moments
/.Upward Forces - Answer-✅Equal to Downward forces
,/.Actual Mechanical Advantage (Ma) - Answer-✅Load (N) / Effort (N)
/.Velocity Ratio (VR) - Answer-✅Distance moved by Effort / Distance moved by Load
/.Efficiency - Answer-✅Output Work / Input Work
/.Output Work - Answer-✅Load x Distance moved by load
/.Input Work - Answer-✅Effort x Distance moved by effort , Equals Output work +
Wasted work
/.Ideal Mechanical Advantage (MA) - Answer-✅Equal to Velocity Ratio (VR)
/.Load x r - Answer-✅Equal to Effort x R
/.VR - Answer-✅Equal to R/r and D/d
/.Load /Effort - Answer-✅Equal to R/r
/.Scalar - Answer-✅A physical quantity that has magnitude but no direction
/.Vector - Answer-✅A quantity that has magnitude and direction
/.Space Diagram - Answer-✅Illustrates a system of vectors
/.Co-planar Vectors - Answer-✅Vectors that are all in the same plane
/.Concurrent Vectors - Answer-✅Vectors whose lines of action meet at one point
/.Resultant - Answer-✅A vector that represents the sum of two or more vectors
/.Absolute Pressure - Answer-✅Atmospheric pressure + gauge pressure
/.Static Friction - Answer-✅A friction force that acts on objects that are not moving.
Always greater than kinetic friction
/.Kinetic Friction - Answer-✅Friction that opposes motion once the motion has already
started. Not affected by speed of body Always greater than rolling friction.
/.Rolling Friction - Answer-✅The friction force that acts on rolling objects, Always less
than kinetic friction
,/.Fluid Friction - Answer-✅Friction that occurs as an object moves through a fluid
/.Force of Friction - Answer-✅Force that resists motion when two materials are in
contact. Proportional to the force that presses the two surfaces together. Not affected by
area. Affected by roughness.
/.Elasticity - Answer-✅The ability of a material to return to its original shape after being
disturbed
/.Stiffness - Answer-✅Ability of a material to resist a change in shape or size when a
load is applied
/.Plasticity - Answer-✅Ability of a material to retain its deformed shape when a
deforming force is removed
/.Ductility - Answer-✅Ability of a material to be stretched and reduced in cross section
without breaking
/.Toughness - Answer-✅Ability of a material to absorb energy before breaking
/.Hardness - Answer-✅Ability of a material to resist penetration
/.Stress - Answer-✅Internal resistance to an external load , Equal to Load (N) / Area
(m^2)
/.Tensile Stress - Answer-✅Forces that act at opposite ends of a bar and pull away
from each other, creating tension on the bar
/.Compressive Stress - Answer-✅A stress due to a force pushing together on a body
/.Shear Stress - Answer-✅Forces on a bar that act parallel to another but are not on the
same plane
/.Ultimate Stress - Answer-✅The stress at which fracture of the material occurs
/.Allowable Stress - Answer-✅The greatest stress which a material is capable of
developing without permanent deformation remaining upon the complete release of
stress.
/.Elastic Limit - Answer-✅Maximum stress that a material will withstand without
permanent deformation. Will return to its original size and shape
/.Factor of Safety - Answer-✅Ultimate Stress / Allowable Stress
, /.Strain - Answer-✅A measure of the deformation produced in a member by a load ,
Equal to Change in Length (l) / Original Length (L)
/.Circumferance - Answer-✅pi x Diameter
/.Linear Speed - Answer-✅Equal to rev/min x pi D / 60
/.Four States of Matter - Answer-✅solid, liquid, gas, plasma
/.Phase - Answer-✅One individual substance in one particular state
/.Chemical Properties - Answer-✅Only observed when there is a chemical change or
reaction , Examples are Heat of combustion, Toxicity, Flammability, Chemical Stability
/.Physical Properties - Answer-✅Characteristics that you can observe without a change
in the composition of matter
/.Intensive Physical Property - Answer-✅Not dependent on the amount of matter
/.Extensive Physical Property - Answer-✅Dependent on the amount of matter
/.Mixture - Answer-✅A combination of two or more substances that are not chemically
combined
/.Homogeneous Mixture - Answer-✅AKA Solution , Only has one set of properties ,
Possible only when all the components are in the same physical state , Ex. Flue gas
/.Heterogenous Mixture - Answer-✅Non-uniform Composition , Substances may or may
not be in the same physical state , Ex. Oil and water emulsion , Sand and water
/.Matter - Answer-✅Can be described in terms of its states, physical, and chemical
properties , State of matter is dependent on its temperature and pressure
/.Pure Substances - Answer-✅Elements and Compounds
/.Atomic Number - Answer-✅Represents the number of protons in an atom
/.First Law of Thermodynamics - Answer-✅The increase in internal energy of a closed
system is equal to the heat supplied to the system minus work done by it (change in
work=change in heat)
/.Second Law of Thermodynamics - Answer-✅Unaided, heat will flow only from a hot
substance to a colder substance
