Energy of Simple Harmonic Oscillators Practice Test

A block on a spring executes SHM on a level surface. When the block is at equilibrium, its kinetic energy is $20,\text{J}$ and its spring potential energy is $0,\text{J}$. At maximum displacement it is momentarily at rest. What is the spring potential energy at maximum displacement?

A cart attached to a spring oscillates on a frictionless track in SHM. The equilibrium position is where the spring is unstretched. At the turning points, the cart’s kinetic energy is $0$ and spring potential energy is maximum. At equilibrium, kinetic energy is maximum and potential energy is minimum. Total mechanical energy is constant. The cart is at $x=+A/\sqrt{2}$.

At $x=+A/\sqrt{2}$, which statement about energy is correct?