  We prove two general theorems which determine the Lie and the Noether point
symmetries for the equations of motion of a dynamical system which moves in a
general Riemannian space under the action of a time dependent potential
$W(t,x)=\omega(t)V(x)$. We apply the theorems to the case of a time dependent
central potential and the harmonic oscillator and determine all Lie and Noether
point symmetries. Finally we prove that these theorems also apply to the case
of a dynamical system with linear dumping and study two examples.
