2023年衡水金卷先享题·高三一轮复习夯基卷(辽宁专版) 地理(一)1试题答案

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5.如图所示，质量均为m的A、B两物体叠放在竖直弹簧上并保持静止，用大小等于mg的恒力F向上拉B,运动距离h时，B与A分离。已知重力加速度为g。下列说法正确的是A.B和A分离瞬间，弹簧长度等于其原长B.B和A分离瞬间，它们的加速度大小为gC弹簧的劲度系数为贤D.在B与A分离之前，它们做匀加速直线运动【答案】C【解析】A、B分离前，A、B共同做加速运动，由于F是恒力，而弹簧弹力是变力，故A、B做变加速直线运动，D错误；当两物体要分离时，FAB=0,对B有F一mg=ma,对A有kx一mg=ma,即F=x时A、B分离，此时弹簧仍处于压缩状态，加速度不等于g,A、B错误；设用恒力F拉B前弹簧的压缩量为x。,则2mg=kxo,h=x。一x,解得k=m坚，C正确。h

作文Earth Hour falls on the last Saturday of March,from 20:30 to 21:30.It was named by theWWF in 2007,aiming to raise people's awareness of the importance of saving electricity.Electricity plays a crucial role in our daily life.Not only does electricity make productionmore efficient,but also it enables people to study,work and have fun at night.Therefore,it is ofvital importance to save electricity.To begin with,whenever we leave our classrooms ordormitories,we should turn off the lights.In addition,it is suggested that all the electric appliancesshould be unplugged when not used.What's more,we are supposed to use air conditioners less,and when we use them,we should keep the temperature above 26C.All in all,it is high time that we devoted ourselves to saving electricity.To save electricity isto save our earth.