Mechanical shocks are complex dynamic phenomena which can appear during the functioning of a structure or equipment. They can be encountered in normal operation (case of forges or automatic pile drivers) or they can be accidentally produced. In the much known cases of shock, a body with a certain mass strikes another body or a structure. Likewise, shocks can be encountered when a force is suddenly applied on a structure or when bodies with known masses (motors) are suddenly turned on or off. The aim of this paper is to determine the dynamic response of a structure due to a mechanical shock produced by a suddenly applied force. The influence of time variation of a force on the dynamic response (shock response spectrum for displacements) of a given structure like a pillar-mounted slewing jib will be analyzed.