EN: Change in height (Δh) is the difference between final and initial height. - It tells how much gravitational potential energy changes: ΔGPE = m g Δh. - Δh depends on the chosen reference level and can be positive or negative.

中文：高度变化（Δh）是末高度与初高度之差。 - 它决定重力势能的变化：ΔGPE = m g Δh。 - Δh 与所选参考高度有关，可为正也可为负。