4th Class Power Engineering Part A Exam questions with
complete solutions
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
complete solutions
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
