题目3单选题
一列高速火车以速度v驶过车站,停在站台上的观测者观测到,固定在站台上相距2 m的两只机械手,同时在车厢上划出两个痕迹,则车厢上的观测者测出这两个痕迹之间的距离为A. <img src="https://tihai-oss-cloud.itihey.com/img/5713bc7446c2fea21c5ea26015fd5232.png">B. <img src="https://tihai-oss-cloud.itihey.com/img/ebe1f8836ef4da3772abef6fc0dbebf2.png">C. <img src="https://tihai-oss-cloud.itihey.com/img/d5dfa2ca580382637e8ad9a22aaca15d.png">D. <img src="https://tihai-oss-cloud.itihey.com/img/eb331eae6fdd97265aeea65dc0633559.png">