An SDF undamped system is subjected to a full-cycle sine pulse force (Fig. P4.19). (a) Derive equations describing u(t) during the forced and free vibration phases. (b) Plot the response u(t)/(us), versus t/T, for various values of ta/T; on the same plots show the static response us(t)/(us). (c) Determine the peak response u., defined as the maximum of the absolute value of u(t), during (i) the forced vibration phase, and (ii) the free vibration phase. (d) Plot Rd=u/(us), for each of the two phases as a function of ta/Tn. (e) Plot the shock spectrum. P -Pa Figure P4.19