A cube, whose mass is 0.560 kg, is attached to a spring with a force constant of 104 N/m. The cube rests upon a frictionless, horizontal surface The cube is pulled to the right a distance A = 0.150 m from its equilibrium position (the vertical dashed line) and held motionless. The cube is then released from rest. At that very instant, what is the magnitude of the cube's acceleration (in m/s2)