A ball bearing is dropped from rest and falls at speed v just before hitting a spring. The spring compresses by a distance of y, and all energy is converted into elastic potential energy in the spring. We are supposed to find F exerted by spring. The conversion of energy, according to me, is 0.5mv2 [KE]-->mgy [GPE] +0.5 Fy [EPE, imagine the Force against Displacement graph and EPE is area under it] However, the answer given is, 0.5mv2-->mgy + Fy [I suppose this is work done] Which is correct and why? Im confused. Thanks.