Prof: It doesn't work?

说不通吗
Would it block more or fewer things if you pulled it back?

被地球挡住的力会增加还是减少呢
Students: Fewer.

减少
Prof: How many fewer?

减多少
Suppose you made it twice as far back,

假设你将地球拉到原来的两倍远
how many fewer would be blocked from hitting the moon?

被地球挡住的力会少多少呢
Student: Wouldn't it be r^2?

不是r^2吗
Prof: It would be 1/r^2.

是1/r^2
You can think about that.

想想看
So that aspect of it would work.

这样想是行的通的
How about-- you know gravity is proportional to the mass of the things.

如你们所知重力正比于质量
How does that figure?

这又是怎么得出来的呢