如果您无法观看此视频，您的浏览器可能不支持HTML5视频
要观看此视频必须开启 JavaScript，请确认浏览器已经设定正确：supports HTML5 video
Beginning of dialog window. Escape will cancel and close the window.
End of dialog window.
No need for gravity with density
Jacois 1 年
Density isn't a force in and of itself. Density/buoyancy being the cause is a controlled-op grift.
Why doesn't density cause things to, "fall", left, right or up? There's a better, logical explanation that can be demonstrated.