  The solution of the time-dependent Schr\"odinger equation is discussed for a
particle confined in half-space $x>0$ with a linear potential $V(x)=Kx$ in the
following situations: (a) sudden removal of the wall and switching on the
linear potential $V(x)=Kx$ at $x \leq 0$, (b) sudden removal of the wall and
the potential and (c) sudden removal of the potential. A brief discussion of
the quantum statistic is presented.
