6 





6.1 
SCALAR [SCALAR QUANTITY] Quantity that is specified by one real number. 

6.2 
VECTOR 1. Directed line segment. 2. Row or column matrix. 

6.3 
VECTOR QUANTITY Quantity which in addition to being geometrically represented by a vector also adds in accordance with the parallelogram/triangle rule. 

6.4 
VECTOR FIELD Region in which every point has a definite vector associated with it. 

6.5 
VECTOR FUNCTION Relationship which determines a vector for every particular value of a scalar parameter. 

6.6 
GRADIENT Vector whose components along the axes of a rectangular system of coordinates at a given point are equal to the partial derivatives of a given scalar function of the coordinates. 

6.7 
POTENTIAL Scalar function whose gradient is the opposite vector to the vector of a given vector field. 

6.8 
VELOCITY HODOGRAPH Locus of the arrowhead of the velocity vectors of a moving point, when all the vectors are drawn from a common origin. 

6.9 
PEAK VALUE: Maximum value of a quantity during a given interval. Note: A peak value of an oscillating quantity is usually taken as the maximum deviation of that quantity from the mean value. 

6.10 
MEANSQUARE VALUE Average of the squared values of a function over a given interval. 

6.11 
ROOTMEANSQUARE [r.m.s.] VALUE Square root of the meansquare value. 

6.12 
TIME HISTORY Magnitude of a quantity expressed as a function of time. 

6.13 
TIME CONSTANT [RELAXATION TIME] Time taken by an exponentially decaying quantity to decrease in magnitude by a factor 1/e=0.3679. 

6.14 
SIGNAL Disturbance used to convey information. 

6.15 
INPUT Disturbance or signal applied to a system. 

6.16 
OUTPUT Response of a system to an input. 

6.17 
NOISE Disturbance, generally of a random nature , which is imposed on the output due to effects not considered in the theoretical model 

6.18 
ACTIVE DEVICE/SYSTEM Device or system with its own independent source of power. 

6.19 
PASSIVE DEVICE/SYSTEM Device whose output energy is supplied entirely through its input. 

6.20 
GENERALIZED COORDINATE One of a set of independent variables which determine uniquely the configuration of a system. 

6.21 
SYSTEM Entirety of components functioning as a whole. 

6.22 
TECHNICAL SYSTEM Practical realisation of a system. 

6.23 
MODEL Idealised, usually simplified representation of a system. 

6.24 
DEVICE Machine or machine component to perform one or more (simple) tasks. 

6.25 
PROCESS Any change of a system and/or its behaviour with respect to time. 

6.26 
PHYSICAL MODEL Model in which physical properties are considered. 

6.27 
SCALE MODEL Physical model in which similarity laws related to the original are considered 

6.28 
MATHEMATICAL MODEL Set of mathematical equations describing the physical properties of a system 

6.29 
MECHANICAL MODEL Physical model in which only the mechanical properties are considered. 

6.30 
DISCRETE MODEL Model described by a finite number of ordinary (differential) equations 

6.31 
CONTINUOUS MODEL Model described by a finite number of partial differential or integral equations 

6.32 
HYBRID MODEL Mechanical model consisting of both discrete model and continuous model elements 