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Coastal Engineering: Theory and Practice
Table 9.1. Unit représentation and scale factor for varions parameters.
Variable
Unit
Remarks
GEOMETRY
Length
L
Any characteristic dimension of the object
Area
L2
Surface area or projected area on a plane
Volume
L3
For any portion of the object
KINEMATICS AND DYNAMICS
Moment of Inertia Area
L4
Moment of Inertia Mass
ML2
Taken about a fixed point
Center of Gravity
L
Measured from a reference point
Time
T
Same reference point (e.g., starting time) is
considered as zéro time
Accélération
LT“ 2
Rate of change of velocity
Velocity
LT”1
Rate of change of displacement
Displacement
L
Position at rest is considered as zéro
Angular Accélération
rp —2
Rate of change of angular velocity
Angular Velocity
T-1
Rate of change of angular displacement
Angular Displacement
None
Zéro degree is taken as reference
Spring Constant (Linear)
MT"2
Force per unit length of extension
Damping Coefficient
MT-1
Résistance (viscous) against oscillation
Damping Factor
None
Ratio of damping and critical damping
coefficient
Natural Period
T
Period at which inertia force = restoring
force
Momentum
MLT"1
Mass times linear velocity
Angular Momentum
ML2T-1
Mass moment of inertia times angular
velocity
Torque
ml2t-2
Tangential force times distance
Work
ml2t~2
Force applied times distance moved
Power
ml2t-3
Rate of work
Impulse
MLT'1
Constant force times its short duration of
time
Force,Thrust, Résistance
MLT"2
Action of one body on another to change or
tend to change the state of motion of the
body acted on
STATICS
Stiffness
ml3t-2
Modulus of elasticity times the moment of
inertia, El
Stress
ml-it-2
Force on an element per unit area
(Continued)