When David rolls it around like this, he's turning the sling around probably at six or seven revolutions per second, and that means that when the rock is released, it's going forward really fast, probably 35 meters per second.
当大卫这样抛旋的时候 速度大约可以达到 每秒六到七圈 这就意味着，当石头被释放出去的时候 它的速度是非常快的 大概每秒35米