U = 12kx². Potential energy of a spring.
E = 12mv² + 12kx². Total energy of a mass-spring system.
E = 12kA². Total energy in a mass-spring system is constant.

Which of the following statements concerning a horizontal mass-spring system in simple harmonic motion is true?
a. The mass has maximum kinetic energy at the same moment is has maximum potential energy.
b. The mass has zero potential energy at the center of the oscillation.
c. The mass has zero kinetic energy at the center of the oscillation.
d. The mass has maximum kinetic energy at the maximum of the oscillation.