题目

Last week Adele's second album, 21, sold 257,000 copies in the UK, a sales figure that would look incredible as an opening sales week for any album by any global superstar. The fact that the album was celebrating its 10th week at No.1, and that each of the previous nine weeks it had sold over 100,000 copies, makes what Adele has achieved look miraculous. The last female singer to spend that long at No.1 in the UK was Madonna in 1990 with her greatest hits compilation, The Immaculate Collection. For Adele, the success of 21 is part of a perfect storm of talent, timing and a connection （12分）A、B两列火车，在同一轨道上同向行驶，A车在前，其速度vA＝10 m/s，B车在后，其速度vB＝30 m/s，因大雾能见度低，B车在距A车x0＝85 m时才发现前方有A车，这时B车立即刹车，但B车要经过180 m才能停止，问：B车刹车时A车仍按原速率行驶，两车是否会相撞？若会相撞，将在B车刹车后何时相撞？若不会相撞，则两车最近距离是多少？