moving in the 
-direction about the equilibrium position 
under the influence of a restoring force 
that is always directed towards and which is proportional to the displacement from that point
of: a particle of mass moving in the -direction about the equilibrium position under the influence of a restoring force that is always directed towards and which is proportional to the displacement from that point
is: an oscillatory form of linear motion in which the displacement of the particle at time 
from an equilibrium position is given by
where the amplitude 
and phase constant 
are arbitrary constants determined by the initial conditions, and the angular frequency 
is a constant determined by the force constant 
and the mass as given by 
[M5.1, P5.4, P5.5]
can be described: by a differential equation (called the SHM equation) of the form:
[M6.3, P5.5]
Copyright 1997, The Open University