往下拉这儿的话,会产生向上的拉力,中间有根弹簧,它能帮助你测出力的大小了。

And if you have a pull down here and you have a pull up here and you have in here a spring then you see you have a way of measuring that force.

youdao

往下拉这儿的话,会产生向上的拉力,中间有根弹簧,它能帮助你测出力的大小了。

And if you have a pull down here and you have a pull up here and you have in here a spring then you see you have a way of measuring that force.

youdao