The classical and quantum probability distributions for both position
and momentum are compared for several model systems admitting bound st
ates including the harmonic oscillator, the infinite well, and the lin
ear confining potential (V(x)=F\x\). Examples corresponding to unbound
systems, including the uniformly accelerating particle and the motion
of a particle moving away from a point of unstable equilibrium, i.e.;
the ''unstable oscillator'' defined by V(x)=-kx(2)/2, are also consid
ered. The quantum and classical distribution of kinetic and potential
energy for the harmonic oscillator is briefly discussed. (C) 1995 Amer
ican Association of Physics Teachers.