A force of 3 N stretches a spring by 1 m. A mass of 4 kg is attached to the spring. At t=0 the mass is pulled down a distance 1 m from equilibrium and released with a downward velocity of 0.5 m/s. Assuming that damping is negligible, determine an expression for the position of the mass at time t. Find the circular frequency of the system and the amplitude, phase, and period of the motion.