物理:在旋轉圓盤上跳起的問題?

No. When the person jumps up, there is no longer any centripetal force acting on him. He will then moves in a straight line (Newton's 1st Law of motion) and will not follow his original circular path.

The case in a train is of different situation, because the train is already moving in a straight line.

不保證正確
不會，由於失去圓盤所給予人的摩擦力作為向心加速度
人不會在原相對位置降落
從地面不動處觀察時，人會依據原本慣性的方向前進
水平地面的速度通常應約略地指向圓盤旋轉切線方向