4th Class Power Engineering Part A Exam
UPDATED ACTUAL Questions and
CORRECT Answers
Velocity (m/s) - CORRECT ANSWER- Change in position / time
Acceleration (m/s^2) - CORRECT ANSWER- Change in velocity (m/s) / time (s)
Force (Newton) - CORRECT 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 - CORRECT ANSWER- mass (kg) x 9.81 m/s^2
Pressure (Pa) - CORRECT ANSWER- Force (N) / area (m^2)
Work (J) - CORRECT ANSWER- Force (N) x distance (m)
Power - CORRECT ANSWER- Work done / time , Rate of doing work
Potential Energy (J) - CORRECT ANSWER- mass x gravity x height , the ability of a body to
do work due by virtue of its position
Kinetic Energy (J) - CORRECT ANSWER- 1/2 x mass x velocity^2 , The ability of a body to
do work due to its motion
Energy (J) - CORRECT ANSWER- The capacity of a body to do work
Tonne - CORRECT ANSWER- 1000 kilograms
Moment of Force (Nm) - CORRECT 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 - CORRECT ANSWER- Equal to Counter-clockwise moments
Upward Forces - CORRECT ANSWER- Equal to Downward forces
Actual Mechanical Advantage (Ma) - CORRECT ANSWER- Load (N) / Effort (N)
Velocity Ratio (VR) - CORRECT ANSWER- Distance moved by Effort / Distance moved by
Load
Efficiency - CORRECT ANSWER- Output Work / Input Work
Output Work - CORRECT ANSWER- Load x Distance moved by load
Input Work - CORRECT ANSWER- Effort x Distance moved by effort , Equals Output work
+ Wasted work
Ideal Mechanical Advantage (MA) - CORRECT ANSWER- Equal to Velocity Ratio (VR)
Load x r - CORRECT ANSWER- Equal to Effort x R
VR - CORRECT ANSWER- Equal to R/r and D/d
Load /Effort - CORRECT ANSWER- Equal to R/r
Scalar - CORRECT ANSWER- A physical quantity that has magnitude but no direction
Vector - CORRECT ANSWER- A quantity that has magnitude and direction
Space Diagram - CORRECT ANSWER- Illustrates a system of vectors
,Co-planar Vectors - CORRECT ANSWER- Vectors that are all in the same plane
Concurrent Vectors - CORRECT ANSWER- Vectors whose lines of action meet at one point
Resultant - CORRECT ANSWER- A vector that represents the sum of two or more vectors
Absolute Pressure - CORRECT ANSWER- Atmospheric pressure + gauge pressure
Static Friction - CORRECT ANSWER- A friction force that acts on objects that are not
moving. Always greater than kinetic friction
Kinetic Friction - CORRECT ANSWER- Friction that opposes motion once the motion has
already started. Not affected by speed of body Always greater than rolling friction.
Rolling Friction - CORRECT ANSWER- The friction force that acts on rolling objects,
Always less than kinetic friction
Fluid Friction - CORRECT ANSWER- Friction that occurs as an object moves through a
fluid
Force of Friction - CORRECT 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 - CORRECT ANSWER- The ability of a material to return to its original shape
after being disturbed
Stiffness - CORRECT ANSWER- Ability of a material to resist a change in shape or size
when a load is applied
Plasticity - CORRECT ANSWER- Ability of a material to retain its deformed shape when a
deforming force is removed
, Ductility - CORRECT ANSWER- Ability of a material to be stretched and reduced in cross
section without breaking
Toughness - CORRECT ANSWER- Ability of a material to absorb energy before breaking
Hardness - CORRECT ANSWER- Ability of a material to resist penetration
Stress - CORRECT ANSWER- Internal resistance to an external load , Equal to Load (N) /
Area (m^2)
Tensile Stress - CORRECT ANSWER- Forces that act at opposite ends of a bar and pull
away from each other, creating tension on the bar
Compressive Stress - CORRECT ANSWER- A stress due to a force pushing together on a
body
Shear Stress - CORRECT ANSWER- Forces on a bar that act parallel to another but are not
on the same plane
Ultimate Stress - CORRECT ANSWER- The stress at which fracture of the material occurs
Allowable Stress - CORRECT ANSWER- The greatest stress which a material is capable of
developing without permanent deformation remaining upon the complete release of stress.
Elastic Limit - CORRECT ANSWER- Maximum stress that a material will withstand without
permanent deformation. Will return to its original size and shape
Factor of Safety - CORRECT ANSWER- Ultimate Stress / Allowable Stress
Strain - CORRECT ANSWER- A measure of the deformation produced in a member by a
load , Equal to Change in Length (l) / Original Length (L)
Circumferance - CORRECT ANSWER- pi x Diameter
UPDATED ACTUAL Questions and
CORRECT Answers
Velocity (m/s) - CORRECT ANSWER- Change in position / time
Acceleration (m/s^2) - CORRECT ANSWER- Change in velocity (m/s) / time (s)
Force (Newton) - CORRECT 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 - CORRECT ANSWER- mass (kg) x 9.81 m/s^2
Pressure (Pa) - CORRECT ANSWER- Force (N) / area (m^2)
Work (J) - CORRECT ANSWER- Force (N) x distance (m)
Power - CORRECT ANSWER- Work done / time , Rate of doing work
Potential Energy (J) - CORRECT ANSWER- mass x gravity x height , the ability of a body to
do work due by virtue of its position
Kinetic Energy (J) - CORRECT ANSWER- 1/2 x mass x velocity^2 , The ability of a body to
do work due to its motion
Energy (J) - CORRECT ANSWER- The capacity of a body to do work
Tonne - CORRECT ANSWER- 1000 kilograms
Moment of Force (Nm) - CORRECT 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 - CORRECT ANSWER- Equal to Counter-clockwise moments
Upward Forces - CORRECT ANSWER- Equal to Downward forces
Actual Mechanical Advantage (Ma) - CORRECT ANSWER- Load (N) / Effort (N)
Velocity Ratio (VR) - CORRECT ANSWER- Distance moved by Effort / Distance moved by
Load
Efficiency - CORRECT ANSWER- Output Work / Input Work
Output Work - CORRECT ANSWER- Load x Distance moved by load
Input Work - CORRECT ANSWER- Effort x Distance moved by effort , Equals Output work
+ Wasted work
Ideal Mechanical Advantage (MA) - CORRECT ANSWER- Equal to Velocity Ratio (VR)
Load x r - CORRECT ANSWER- Equal to Effort x R
VR - CORRECT ANSWER- Equal to R/r and D/d
Load /Effort - CORRECT ANSWER- Equal to R/r
Scalar - CORRECT ANSWER- A physical quantity that has magnitude but no direction
Vector - CORRECT ANSWER- A quantity that has magnitude and direction
Space Diagram - CORRECT ANSWER- Illustrates a system of vectors
,Co-planar Vectors - CORRECT ANSWER- Vectors that are all in the same plane
Concurrent Vectors - CORRECT ANSWER- Vectors whose lines of action meet at one point
Resultant - CORRECT ANSWER- A vector that represents the sum of two or more vectors
Absolute Pressure - CORRECT ANSWER- Atmospheric pressure + gauge pressure
Static Friction - CORRECT ANSWER- A friction force that acts on objects that are not
moving. Always greater than kinetic friction
Kinetic Friction - CORRECT ANSWER- Friction that opposes motion once the motion has
already started. Not affected by speed of body Always greater than rolling friction.
Rolling Friction - CORRECT ANSWER- The friction force that acts on rolling objects,
Always less than kinetic friction
Fluid Friction - CORRECT ANSWER- Friction that occurs as an object moves through a
fluid
Force of Friction - CORRECT 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 - CORRECT ANSWER- The ability of a material to return to its original shape
after being disturbed
Stiffness - CORRECT ANSWER- Ability of a material to resist a change in shape or size
when a load is applied
Plasticity - CORRECT ANSWER- Ability of a material to retain its deformed shape when a
deforming force is removed
, Ductility - CORRECT ANSWER- Ability of a material to be stretched and reduced in cross
section without breaking
Toughness - CORRECT ANSWER- Ability of a material to absorb energy before breaking
Hardness - CORRECT ANSWER- Ability of a material to resist penetration
Stress - CORRECT ANSWER- Internal resistance to an external load , Equal to Load (N) /
Area (m^2)
Tensile Stress - CORRECT ANSWER- Forces that act at opposite ends of a bar and pull
away from each other, creating tension on the bar
Compressive Stress - CORRECT ANSWER- A stress due to a force pushing together on a
body
Shear Stress - CORRECT ANSWER- Forces on a bar that act parallel to another but are not
on the same plane
Ultimate Stress - CORRECT ANSWER- The stress at which fracture of the material occurs
Allowable Stress - CORRECT ANSWER- The greatest stress which a material is capable of
developing without permanent deformation remaining upon the complete release of stress.
Elastic Limit - CORRECT ANSWER- Maximum stress that a material will withstand without
permanent deformation. Will return to its original size and shape
Factor of Safety - CORRECT ANSWER- Ultimate Stress / Allowable Stress
Strain - CORRECT ANSWER- A measure of the deformation produced in a member by a
load , Equal to Change in Length (l) / Original Length (L)
Circumferance - CORRECT ANSWER- pi x Diameter
