For example, how do I know

例如怎样才能知道
that when I pull the spring the first time for the mass,

第一次连着物体拉弹簧时
it exerted the same force

产生的力和
when I pulled the spring the second time for the elephant?

第二次连着大象拉弹簧时产生的力是相等的呢
After all, springs wear out.

毕竟弹簧是会坏掉的
That's why you change your shock absorbers in your car.

这也就是你定期更换爱车的减震器的原因
After a while, they don't do the same thing.

过一段时间它们就不能正常工作了
First, we got to make sure

首先要保证
the spring exerts a fixed force every time.

弹簧每次产生的力是恒定的
You can say, "How am I going to check that?

你就会问了 "我怎么才能确认这一点呢
I don't have the definition of force yet."

我还不知道力的定义是什么"
But we do know the following.

但我们知道如下内容