2022 英语周报 高二 外研综合 1答案

25.解析:(1)根据题意可知,粒子出电场时,平行电场方向的分速度r=r0(1分)粒子第一次在电场中运动时间1=(1分)设粒子在电场中运动的加速度大小为a,则t=at1(1分)设匀强电场的电场强度大小为E,根据牛顿第定律有qE=ma(1分)解得E-m2(2(2)设粒子第次出电场时的速度大小为r,根据题意可知,=2n(1分)粒子在电场、磁场中的运动轨迹如图所示。设粒子在磁场中做圃周运动的半径为r根据儿何关系,+r=R(1分xxX解得r=(√2-1)R(1分)根据牛顿第二定律B=m(2分)解得B(2+5)m(2分)1.5R(3)粒子出电场后、进磁场前运动的时间t2=(3-2)K(1分)粒子在磁场中运动的时间t352mm27rm27(2-2)m(1分)粒子出磁场后、第次进电场前运动的时间=0.58=2R(1分粒了第二次在电场中运动的时间,=R=2R(1分)因此运动的总时间t=+2+++=48(10+2)+27(2-2)mR(3分)
书面表达One possible version:NOTICEA sports meeting will be held in the playground of our school from next Thursday to FridayAs you know, the pressure of study is very heavy now, especially for those senior 3. So the purpose of the sports meeting is to letevery student get relaxed, as a result of which we students can live happily and heal thilyEveryone is welcome to take part in it. Those who perform excellently at the sports meeting will get prizes. But don' t take theresults so serously because taking part is more important than the result. Good luck to everyone!
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