Potential Energy Practice Test

A block is released from rest while attached to a vertical spring. Define $U_s=0$ when the spring is unstretched. At instant $A$ the spring is stretched $0.08,\text{m}$; at instant $B$ it is stretched $0.16,\text{m}$. Which statement about $U_s$ is correct?

A cart is on a frictionless track in Earth’s gravitational field. The reference level is the floor ($U_g=0$ at $h=0$). At point $P$, the cart is at height $h=2.0,\text{m}$. At point $Q$, the cart is at height $h=5.0,\text{m}$. Which statement about gravitational potential energy is correct?