A seismic instrument is constructed so that m $=0\mathrm{.}45$ kg and c $.$ Acc$707.0$spring with k $=2\mathrm{.}9$ kN$/$m is used so that the instrument will be relativelyinsensitive to low$-$frequency signals for displacement measurements andrelatively insensitive to high$-$frequency measurements. Calculate the value ofthe linear acceleration that will produce a relative displacement of $2\mathrm{.}5$ mmwhile the frequency is $20$Hz$.$