Flight safety , not to be pedantic . Wouldn't the dumbell after beeing released actually hit the ground several feet behind you , unless of course your assistant managed to stop the roundabout the instant after you let go of the dumbell. I guess if the roundabout also managed to do one full rotation while the dumbell was airborne that would count too. In fact id you are going in a circle what is behind you is in front of you as well. Dohhhh.