1. The problem statement, all variables and given/known data If the phase angle for a block-spring system in SHM is π/5 rad and the block's position is given x = xm cos(ωt + phi), what is the ratio of the kinetic energy to the potential energy at time t = 0? 2. Relevant equations PE = (1/2)*k*[(max amplitude)^2]*cos^2(ωt + phi) KE = (1/2)*k*[(max amplitude)^2]*sin^2(ωt + phi) Solve for KE/PE in that form. 3. The attempt at a solution I took KE and divided by PE, giving sin^2(phi)/cos^2(phi). Plugging in pi/5 for phi gives us 1.20253316E-4/.99987974669. However, the system is saying this is wrong . I do believe that I solved for KE/PE correctly. Any help would be much appreciated. Thanks very much!