Abstract The deformation of a thin flat metal disk under the influence of a transverse load is described, and the response times for the particular case of a copper disk have been determined experimentally. It is shown that the deflexion under shock loading conditions can be explained on the assumption that deformation is due to the combined action of inertia and strain waves. Comparison is made with the deflexion of an extensible wire under similar conditions and it is concluded that this simple analogy could be used as a basis for subsequent analysis.