A block with a mass of 2 kg hangs without vibrating at the end of a spring which is attached to the ceiling of an elevator. The spring constant is 800 N/m. The elevator is moving upwards with an acceleration. Take the upward direction to be positive. (g = 10 m/s) By what amount is the spring stretched during the time when the elevator is accelerating with respect to initial spring length? What is the amplitude of oscillation observed by a person inside the elevator after the acceleration becomes zero?