At t = 0 a block with mass m = 5 kg moves with a velocity v = 2 m/s at position xo = -. 33 m from the equilibrium position of the spring. The block is attached to a massless spring of spring constant k = 61. 2 n/m and slides on a frictionless surface. At what time will the block next pass x = 0, the place where the spring is unstretched?.