2022-20221英语周报七年级答案

16.(1)17J(2)75J(3)v<2m/s或v>5m/s【解析】(1)滑块离开斜面后,竖直方向根据竖直上抛运动规律可得v:=ugh(1分)设滑块运动到N点时,水平速度为v,根据tan(1分)解得v0=23m/s(1分)对滑块,从开始到恰好飞上传送带,根据能量守恒可得Ep=mg(rsin 30 h)tomv(1分)解得Ep=17J(1分)(2)滑块飞上传送带后,对滑块有(1分)解得a=53m/s2设从物块滑上传送带到与传送带共速所用时间为t,由运动学公式得v传=v0 at(1分)解得t=1s则x传=v传t=7√3m(1分x物=v0t -at3-93(1分)相三x传一了物解得x=53(1分)Q=mgx相=75J(1分)(3)若滑块不能越过四分之一圆弧,对滑块根据动能定理有mvi=mgR(1分)解得v1=√2m/s若滑块越过四分之一圆弧,在圆弧轨道最高点对滑块有mgmR(1分)解得vo=1m/s从圆弧轨道最低点到最高点对滑块根据动能定理有R=Imin(1分)解得v2=√5m/s(1分)所以传送带运行速度v需要满足v<2m/s或v>5m/s(1分)

【语篇导读】本文是一篇记叙文,主要讲述了主人公Andy在上学途中遭遇蜂群攻击,急中生智,躲入水中避险成功的故事4.D【解析】细节理解题。根据第一段 He was so busydreaming about all the fish he would catch that he wasaware of everything else around him可知,Andy正忙于做抓鱼的白日梦,没有意识到他周围的事情。与D选项,他的思绪沉浸于钓鱼之旅相符。故选D5.D【解析】细节理解题。根据第二段 a huge swarmof bees filled the sky like a black cloud and the buzzingmass seened to be heading angrily towards him. e X大群蜜蜂像乌云一样布满天空而嗡嗡作响的蜂群似乎正怒气冲冲地向他飞来。可知,A.蜂群像乌云样,C.蜜蜂想成群攻击Andy均有提到;根据第二段What he saw shocked and terrified him,Andy看到的景象吓坏了他,可知B选项也有提到;根据第三段第五句话和第六句话,可知Andy上次被蜜蜂蛰过一次后进了医院住了两天,D选项偷换了概念,故D选项文章并未提到。故选D。6.C【解析】细节理解题。根据第五段 Off his bike andinto the cool water he dived, disappearing below the surface and away from the savage insects. After holding hisbreath for as long as he could, Andy came up for air andnoticed the bees had gone.Andy下了车潜入了水中,躲开了蜂群,在屏息了尽可能长的时间后Andy出来发现蜜蜂已经飞走了。故选C。7.B【解析】推理判断题。根据最后一段Andy的妈妈说的 Thank goodness you didn’ t panIC,谢天谢地你没有慌神,可知情急之下Andy仍然成功想到办法脱险。故选B

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