17. Periodic Motion

If the amplitude of a simple harmonic oscillator doubles, what happens to its total mechanical energy?

A block of mass 0.300 kg is attached to a spring. At x = 0.240 m, its acceleration is a_x= -12.0 m/s² and its velocity is v_x=4.00 m/s. What are the system's (a) force constant k and (b) amplitude of motion?