4th Class Power Engineering Part A
Exam questions 100% answered.
Velocity (m/s) ANS - Change in position / time
Acceleration (m/s^2) ANS - Change in velocity (m/s) / time (s)
Force (Newton) ANS - 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 ANS - mass (kg) x 9.81 m/s^2
Pressure (Pa) ANS - Force (N) / area (m^2)
Work (J) ANS - Force (N) x distance (m)
Power ANS - Work done / time , Rate of doing work
Potential Energy (J) ANS - mass x gravity x height , the ability of a body to do work due by virtue of its
position
Kinetic Energy (J) ANS - 1/2 x mass x velocity^2 , The ability of a body to do work due to its motion
Energy (J) ANS - The capacity of a body to do work
,Tonne ANS - 1000 kilograms
Moment of Force (Nm) ANS - 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 ANS - Equal to Counter-clockwise moments
Upward Forces ANS - Equal to Downward forces
Actual Mechanical Advantage (Ma) ANS - Load (N) / Effort (N)
Velocity Ratio (VR) ANS - Distance moved by Effort / Distance moved by Load
Efficiency ANS - Output Work / Input Work
Output Work ANS - Load x Distance moved by load
Input Work ANS - Effort x Distance moved by effort , Equals Output work + Wasted work
Ideal Mechanical Advantage (MA) ANS - Equal to Velocity Ratio (VR)
Load x r ANS - Equal to Effort x R
VR ANS - Equal to R/r and D/d
Load /Effort ANS - Equal to R/r
Scalar ANS - A physical quantity that has magnitude but no direction
,Vector ANS - A quantity that has magnitude and direction
Space Diagram ANS - Illustrates a system of vectors
Co-planar Vectors ANS - Vectors that are all in the same plane
Concurrent Vectors ANS - Vectors whose lines of action meet at one point
Resultant ANS - A vector that represents the sum of two or more vectors
Absolute Pressure ANS - Atmospheric pressure + gauge pressure
Static Friction ANS - A friction force that acts on objects that are not moving. Always greater than kinetic
friction
Kinetic Friction ANS - Friction that opposes motion once the motion has already started. Not affected by
speed of body Always greater than rolling friction.
Rolling Friction ANS - The friction force that acts on rolling objects, Always less than kinetic friction
Fluid Friction ANS - Friction that occurs as an object moves through a fluid
Force of Friction ANS - 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 ANS - The ability of a material to return to its original shape after being disturbed
Stiffness ANS - Ability of a material to resist a change in shape or size when a load is applied
Plasticity ANS - Ability of a material to retain its deformed shape when a deforming force is removed
, Ductility ANS - Ability of a material to be stretched and reduced in cross section without breaking
Toughness ANS - Ability of a material to absorb energy before breaking
Hardness ANS - Ability of a material to resist penetration
Stress ANS - Internal resistance to an external load , Equal to Load (N) / Area (m^2)
Tensile Stress ANS - Forces that act at opposite ends of a bar and pull away from each other, creating
tension on the bar
Compressive Stress ANS - A stress due to a force pushing together on a body
Shear Stress ANS - Forces on a bar that act parallel to another but are not on the same plane
Ultimate Stress ANS - The stress at which fracture of the material occurs
Allowable Stress ANS - The greatest stress which a material is capable of developing without permanent
deformation remaining upon the complete release of stress.
Elastic Limit ANS - Maximum stress that a material will withstand without permanent deformation. Will
return to its original size and shape
Factor of Safety ANS - Ultimate Stress / Allowable Stress
Strain ANS - A measure of the deformation produced in a member by a load , Equal to Change in Length
(l) / Original Length (L)
Circumferance ANS - pi x Diameter
Exam questions 100% answered.
Velocity (m/s) ANS - Change in position / time
Acceleration (m/s^2) ANS - Change in velocity (m/s) / time (s)
Force (Newton) ANS - 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 ANS - mass (kg) x 9.81 m/s^2
Pressure (Pa) ANS - Force (N) / area (m^2)
Work (J) ANS - Force (N) x distance (m)
Power ANS - Work done / time , Rate of doing work
Potential Energy (J) ANS - mass x gravity x height , the ability of a body to do work due by virtue of its
position
Kinetic Energy (J) ANS - 1/2 x mass x velocity^2 , The ability of a body to do work due to its motion
Energy (J) ANS - The capacity of a body to do work
,Tonne ANS - 1000 kilograms
Moment of Force (Nm) ANS - 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 ANS - Equal to Counter-clockwise moments
Upward Forces ANS - Equal to Downward forces
Actual Mechanical Advantage (Ma) ANS - Load (N) / Effort (N)
Velocity Ratio (VR) ANS - Distance moved by Effort / Distance moved by Load
Efficiency ANS - Output Work / Input Work
Output Work ANS - Load x Distance moved by load
Input Work ANS - Effort x Distance moved by effort , Equals Output work + Wasted work
Ideal Mechanical Advantage (MA) ANS - Equal to Velocity Ratio (VR)
Load x r ANS - Equal to Effort x R
VR ANS - Equal to R/r and D/d
Load /Effort ANS - Equal to R/r
Scalar ANS - A physical quantity that has magnitude but no direction
,Vector ANS - A quantity that has magnitude and direction
Space Diagram ANS - Illustrates a system of vectors
Co-planar Vectors ANS - Vectors that are all in the same plane
Concurrent Vectors ANS - Vectors whose lines of action meet at one point
Resultant ANS - A vector that represents the sum of two or more vectors
Absolute Pressure ANS - Atmospheric pressure + gauge pressure
Static Friction ANS - A friction force that acts on objects that are not moving. Always greater than kinetic
friction
Kinetic Friction ANS - Friction that opposes motion once the motion has already started. Not affected by
speed of body Always greater than rolling friction.
Rolling Friction ANS - The friction force that acts on rolling objects, Always less than kinetic friction
Fluid Friction ANS - Friction that occurs as an object moves through a fluid
Force of Friction ANS - 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 ANS - The ability of a material to return to its original shape after being disturbed
Stiffness ANS - Ability of a material to resist a change in shape or size when a load is applied
Plasticity ANS - Ability of a material to retain its deformed shape when a deforming force is removed
, Ductility ANS - Ability of a material to be stretched and reduced in cross section without breaking
Toughness ANS - Ability of a material to absorb energy before breaking
Hardness ANS - Ability of a material to resist penetration
Stress ANS - Internal resistance to an external load , Equal to Load (N) / Area (m^2)
Tensile Stress ANS - Forces that act at opposite ends of a bar and pull away from each other, creating
tension on the bar
Compressive Stress ANS - A stress due to a force pushing together on a body
Shear Stress ANS - Forces on a bar that act parallel to another but are not on the same plane
Ultimate Stress ANS - The stress at which fracture of the material occurs
Allowable Stress ANS - The greatest stress which a material is capable of developing without permanent
deformation remaining upon the complete release of stress.
Elastic Limit ANS - Maximum stress that a material will withstand without permanent deformation. Will
return to its original size and shape
Factor of Safety ANS - Ultimate Stress / Allowable Stress
Strain ANS - A measure of the deformation produced in a member by a load , Equal to Change in Length
(l) / Original Length (L)
Circumferance ANS - pi x Diameter
