Rotor blade for a wind turbine system and method for damping vibrations of a rotor blade

The invention relates to a rotor blade (1), in particular for a wind energy installation, having at least one Massenaktor (4). Furthermore, the invention relates to a method for damping vibrations of such a rotor blade (1). For effective vibration damping with little space the mass (6) of the Massenaktors (4) in a reciprocating motion is linear or arcuately movable.