A 3.5 kg mass is given an initial position of .75 m on a horizontal spring (k : 250 N/m). Determine (a) the period and frequency of the motion, (b) what is the position, velocity, and acceleration after 20 seconds c.) What is the total energy of the system and the kinetic and potential energy at 20 seconds? d.) At what time is the mass at half its max amplitude? e.) At what time does the mass have half its max velocity?