A 2 kg mass attached to a spring is undergoing simple harmonic motion with a period of 3.9 s and an amplitude of 4.5 m. (a) What is the total energy of the system? (b) What is the maximum speed of the mass? m/s (c) What is the speed of the particle at the position 55' = 1.9 m? m/s (d) What is the elastic potential energy, U, of the system when the mass is moving at half its maximum speed