Newton proved his idea by measuring how much gravity force would be needed to keep the moon orbiting the Earth.

VOA: special.2011.06.01

The poet, after all, is subject to gravity in Frost, to the force of the earth.

这个诗人，弗罗斯特，终究还是受制于地心引力，受制于地球的力量。

耶鲁公开课 - 现代诗歌课程节选

One says, leave any body near the Earth, it yields a force.

有人说,在地球表面的任何物体,都会受到力的作用

耶鲁公开课 - 基础物理课程节选

For example, we know that if a body is near the surface of the Earth, the force of gravity of that object seems to be m times g, where g is 9.8.

例如,我们知道,如果在地球表面有一个物体,该物体受到的重力大小为 m 与 g 的乘积,g 等于 9.8

耶鲁公开课 - 基础物理课程节选