A 2.8 kg block is dropped from a height of 5.8 m (above the top of the spring) onto a spring of spring constant 3955 N/m. Find the speed of the block when the compression of the spring is 15.0 cm. x=0.15m k=3955N/m m=2.8kg Einitial mech=Efinal mech Usi+Ugi+Ki=Usf+Ugf+Kf Usi=0 because the spring is uncompressed Ugi=??? Ki=.5mvi2 where [tex]V_i =sqrt(2g*5.8m)=10.868[/tex] Usf=.5kx2 Ugf=0 because I can set the height at that point to be 0 Kf=.5mvf2 where we're solving for v How do I calculate the potential graviational energy? I'm guessing I need to find out how far the block would go if it were allowed to come to a rest, but I get an impossible to solve equation, or maybe I just don't remember what to do. Block at rest: Usi+Ugi+Ki=Usf+Ugf+Kf 0+mgx + .5mv2i=.5kx2 x(mg-.5kx)=-.5mvi2 x(27.468-1977.5x)=-165.359 x=???