A 20-kg mass was initially at rest, attached to the end of a vertically hanging spring. When given an initial downward velocity of 2 m/s from its equilibrium rest position, the mass was observed to attain a maximum displacement of 0.2m from its equilibrium position. What is the value of the spring constant k? Please help me. I cannot figure this one out. I think the equation is just mg-kdeltay=0 but I cant figure it out. I know 20 kg is the mass. w=mg=20(9.8)=196. Thanks in advance for all of your help!