  We investigate the motion of an inert (massive) particle being impinged from
below by a particle performing (reflected) Brownian motion. The velocity of the
inert particle increases in proportion to the local time of collisions and
decreases according to a constant downward gravitational acceleration. We study
fluctuations and strong laws of the motion of the particles. We further show
that the joint distribution of the velocity of the inert particle and the gap
between the two particles converges in total variation distance to a stationary
distribution which has an explicit product form.
