Relaxed spring is sitting on a horizontal surface. A block is attached at one of its ends is kicked with a horizontal velocity, v1, given to it. The block will move and stretch. Find the distance, x, the spring will stretch. X is in meters. Energy 1/2 mv1^2 = 1/2 mv2^2 + 1/2 k x^2 Angular momentum mv1l0 = mv2(l0+x) The problem was solved using kinetic energy and conservation of angular momentum formulas. My question is, why doesn't m(v^2/r)=kx apply for this problem? Is it because m(v^2/r) is to only be used in uniform circular motion and the object in the problem moves in the shape of an ellipse?