Gravity is the attraction, or pull, of one object on another object.

引力是一个物体对另一个物体所产生的吸引力，或拉力。

The first experiment had nothing whatever to do with gravity, the attraction of the earth.

第一个实验跟重力，即地球的引力无关。

The law of gravity describes and quantifies the attraction between two objects.

地心引力法则描述和量化了两个物体间的吸引力。