[熱身賽第一輪] 位能 [Warm-up Round 1] Potential Energy

unit: Work, Energy, and Power topic: Potential Energy learning objective: Describe the potential energy of a system. essential knowledge: Systems interacting via conservative forces have potential energy associated with their configuration. For an ideal spring the elastic potential energy is $\frac{1}{2} k (\Delta x)^2$. Gravitational potential energy for two spherical masses is $U = -G m_1 m_2 / r$.