Final answer:
An object has maximum acceleration in simple harmonic motion when it is at the equilibrium position, which corresponds with zero displacement.
Step-by-step explanation:
An object moving in simple harmonic motion has maximum acceleration when it has zero displacement from its equilibrium position. This is because the acceleration in simple harmonic motion is proportional to the displacement from the equilibrium position, but in the opposite direction, following Hooke's law. At maximum displacement, the object has maximum potential energy and minimum kinetic energy, and at zero displacement, it has maximum kinetic energy and minimum potential energy. Therefore, the object's maximum acceleration occurs when it is at the equilibrium position where its velocity is also at its maximum. At this point, all the potential energy has been converted into kinetic energy.