题目

       请认真阅读下面短文，从短文后各题所给的A、B、C、D四个选项中，选出最佳选项，并在答题卡上将该项涂黑。        People do not analyze every problem they meet．Sometimes they try to remember a solution from the last time they had a  36  problem．They often accept the opinions or ideas of other people．Other times they begin to act without   37  ; they try to find a solution by trial and error．However, when all of these methods   38  , the person with a problem has to start analyzing．There are six   39   in analyzing 如图所示，一位质量m＝60 kg参加“挑战极限”的业余选手，要越过一宽度为s＝2.5 m的水沟，跃上高为h＝2.0 m的平台，采用的方法是：人手握一根长L＝3.25 m的轻质弹性杆一端，从A点由静止开始匀加速助跑，至B点时，杆另一端抵在O点的阻挡物上，接着杆发生形变、同时脚蹬地，人被弹起，到达最高点时杆处于竖直，人的重心在杆的顶端，此刻人放开杆水平飞出，最终趴落到平台上，运动过程中空气阻力可忽略不计． (1)设人到达B点时速度vB＝8 m/s，人匀加速运动的加速度a＝2 m/s2，求助跑距离sAB． (2)人要到达平台，在最高点飞出时刻速度v至少多大？(取g＝10 m/s2)