a heavy$-$duty stapling gun uses a $0\mathrm{.}136$ kg metal rod that rams against the staple to eject it$.$ the rod is pushed by a stiff spring called a "ram spring" $($k $=35900$ N$/$m$).$ the mass of this spring may be ignored. squeezing the handle of the gun firdt compressed the ram spring by $4\mathrm{.}78$ cm from its unstrained length and then released it$.$ assuming that the ram spring is oriented vertically and is still compressed by $1\mathrm{.}54$ cm when the downward$-$moving ram hits the staple, find the speed of the ram at the instant of contact