However, there are light arm troops made up of those too poor to be in the phalanx, who do use projectiles and the projectiles are arrows, javelins, or stones thrown by slings.

然而的确有轻装部队,由没法进入方阵的穷人组成,他们使用投掷武器,包括弓箭,投枪,或者绳索绑着的石头

耶鲁公开课 - 古希腊历史简介课程节选

You can see that if a was equal to g, your downward acceleration is that of gravity, namely the cable has snapped in the elevator, Then you don't feel any weight.

你会发现如果 a 等于 g,你下降的加速度就是重力加速度,也就是电梯的绳索断了,那时你会完全失重

耶鲁公开课 - 基础物理课程节选