万有引力
Universal Gravitation
描述引力是所有有质量物体之间普遍存在的吸引力，解释轨道运动是因为引力提供向心力，使物体保持在轨道上，并比较不同行星上的引力场强度。
Describe gravity as a universal attractive force between all masses, explain that orbital motion arises because gravity provides the centripetal force keeping objects in orbit, and compare gravitational field strengths on different planets
学习证据 / Evidence
- 说明引力是作用于所有有质量物体之间的普遍吸引力。
- 解释轨道运动的发生是因为引力不断使绕行物体的路径发生偏转。
- 比较不同行星上的引力场强度，并解释这如何影响重量。
- States that gravity is a universal attractive force acting between all objects with mass
- Explains that orbital motion occurs because gravity continuously deflects the path of the orbiting object
- Compares gravitational field strength on different planets and explains how this affects weight
评估问题 / Assessment
如果{{name}}被问到为什么月球不会飞向太空，也不会撞上地球，能否解释为引力一直在使它沿弯曲的路径运动——就像用绳子甩动一个球一样？
If {{name}} was asked why the Moon doesn't fly off into space but also doesn't crash into Earth, could they explain that gravity is constantly pulling it into a curved path — like swinging a ball on a string?