The Speed of Sound

So what you got to do is launch something fast enough that it gets out of the gravitational field before the field can slow it down. And if it can bounce, so the potential energy you let go, it accelerates down bounces and ignoring losses comes back up to roughly the same height. So we call the speed of sound Mark one. The small thing is like a third book. Three times is high. Right. Ah I think it, ah, onto a winner here.