a cord with a spring constant of 100N/m has a 2.0kg block suspended from it. the length of the cord when it is unstretched is .5m. the block is released. determine the length of the cord when it is at the maximum length of elongation. my attempt: first determine the kinetic energy of the block just before the block reaches the point where the cord begins to elongate beyond the length of .5m it is after this point that kinetic energy then begins to be converted into potential spring energy in the cord. it is this energy combined with the weight of the block that are going to determine the maximum length of elongation of the cord. this is because when all of the kinetic energy of the block is turned into potential spring energy the only remaining force that would cause the cord to further elongate would be the weight of the block pulling down on the cord. First, to determine the extension of the spring due to the weight of the block use f=kx 9.8 x 2 = 100x x=0.196 then to determine the energy that this causes to be stored in the cord use E=1/2kx^2 1/2(100)(.196)^2=.98 J this energy combined with the energy that the kinetic energy provides should determine the total length of elongation of the cord .98 + (2 x 9.8 x .5) = 1/2(100)x^2 x=.464327m can someone tell me where im going wrong?