‏一花样滑冰者做原地旋转动作，两臂伸开时，转动惯量为<img src="https://static.zxtiku.com/wangke/imgs/topic/875e23954a0b31e05c4b18789825b9f1.png"/>，角速度为<img src="https://static.zxtiku.com/wangke/imgs/topic/9028466060bbb8f3609655e0e1e390ba.png"/>，其转动动能为<img src="https://static.zxtiku.com/wangke/imgs/topic/fbfd38e482afc8dcc7f2c63ce7c9c1ce.png"/>；然后他将手臂收回，转动惯量变为<img src="https://static.zxtiku.com/wangke/imgs/topic/2a2860a06311c767806d230d7b2c5031.png"/>，此时他的角速度变为<img src="https://static.zxtiku.com/wangke/imgs/topic/994c40e64091b4f9b6e00e4636c86302.png"/>，转动动能变为<img src="https://static.zxtiku.com/wangke/imgs/topic/febb64fd9013db9f9c067206a153d807.png"/>，则（）‏<b