gravity model

例句：

1. 1. The gravity model is widely used in the study of planetary motion.
   重力模型在行星运动研究中被广泛使用。
2. 2.The gravity model has been proven to be effective in predicting earthquakes.
   重力模型已被证明在预测地震方面是有效的。
3. 3.The gravity model provides a simple and intuitive way to understand the relationship between gravity and mass.
   重力模型提供了一个简单直观的方式来理解重力与质量之间的关系。