如图为一单摆装置，把小球从平衡位置<img src="https://static.zxtiku.com/wangke/imgs/topic/c7bf94977c2828423c3d0c418bbb1399.jpg"/>拉开一小角度<img src="https://static.zxtiku.com/wangke/imgs/topic/2b60c9d46fb9183717156f62af1188c5.jpg"/>至<img src="https://static.zxtiku.com/wangke/imgs/topic/81cfc66d1f7613e07bfb3545b8b5c08b.jpg"/>点。在<img src="https://static.zxtiku.com/wangke/imgs/topic/6d4946833d6844e4526b353c72f9f3a2.jpg"/>时刻，放手让其摆动，摆动规律用余弦函数表示。下列说法哪一个是正确的（）<br/> <img src="https://static.zxtiku.com/wangke/imgs/topic/29606c6975dc666f2fc05226a3ab3991.jpg"/><br/> A、<img src="https://static.zxtiku.com/wangke/imgs/topic/416922c7ed7d307040438a9bd06de356.jpg"/>处，动能最小，相位为<img src="https://static.zxtiku.com/wangke/imgs/topic/95eadf12f73fe86ac51d0628b2505b80.jpg"/><br/> B、<img src="https://static.zxtiku.com/wangke/imgs/topic/beb8f65a704ee9b44285af842f6891e4.jpg"/>处，动能最大，相位为<img src="https://static.zxtiku.com/wangke/imgs/topic/6d24d2a593fb7af8d68e0bec7f53c97a.jpg"/><br/> C、<img src="https://static.zxtiku.com/wangke/imgs/topic/b7253658e7ef8cb55ce0dc8d2534a395.jpg"/>处，动能为零，相位为<img src="https://static.zxtiku.com/wangke/imgs/topic/f92cb2725c64324daf2e0aa5fa6670de.jpg"/><br/> D、<img src="https://static.zxtiku.com/wangke/imgs/topic/33ab6fdac56f3747badc98e45e9db12a.jpg"/>三位置能量相同，初相不同