
77Integration of Newton’s Equation of Motion
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where the value of
=
may be either positive or negative. If it is positive, then V(x)– V(x
e
)
is positive, whatever the value of x, so that V(x) is minimum at x. If a particle is situated at x
e
and
experiences a slight disturbance, it will return to x
e
when the disturbance is removed. Equilibrium
of this kind is called stable equilibrium. On the other hand, if
d/d
Vx
=
is negative, then V(x)<
V(x
e
). If the particle is slightly displaced from x
e
, it will move away from its original position of
equilibrium when the disturbance is removed. Equilibr