英语周报高一11新课标答案

34.(1)ACD【解析】由波的图象可知A=8m,根据v÷可得T=0.8s,在△=0.58-0.2s=0.3时间内波传播的距离为△x=v△=3m,对照图线可知波沿x轴正方向传播,A项正确;根据r=0.2s时刻的波动图象,可判断K、L、M三个质点中,L质点最先到达平衡位置,B项错误:=0时刻,x=0处的质点处于平衡位置且同y轴正方向运动,其做简谐运动的表达式为y=10sin2.5mt(m),C项正确;t=0时刻,x=2m处的质点处于波谷,0-0.2s时间内x=2m处的质点向平衡位置运动,速度逐渐增大,D项正确;同一时刻相对平衡位置位移相等的质点,其加速度一定相同,速度大小相等,速度方向可能同向也可能反向,E项错误(2)【解析】如图所示,光源S发出的一条光线射到球面上的P点(2-3)R由正弦定理得R=(2=0③=m(1B=B(3分)可得sinb=(3-1)snp(1分)可得sin=(3-1)sinB(1分)对于位置固定的光源S,当B越大时,光线入射到介质球面的入射角日就越大,光线越容易发生全反射,当入射角8恰等于临界角C时,在P点恰发生全反射,P点下方区域不会有光线射出(1分)(2分)sin C-√6+联立可得sin可得aB-C=30°(1分)由对称性可知,球缺表面被照亮的区域的球冠面积S-2nR(R- Rcos a)nR(2-3)(2分

To be a firefighter look like a pretty cool job. And there are a lot of things you have to doto get this job. First, we must take health-training courses, and thats just a start. Then you canyactually apply for the jobs as a firefighter. After that, theres an written exam. If you pass thetest, you then have to take in a physical exam. It's really hard and a lot of people fail, Amakesure you're in good shape. Next, you go to the fire academy, in that you study for four monthswhichAt this school, you learn to becoming a firefighter. Final, you have to pass your final exam. ItsbecomeFinallytotally stressed but worth itstressful

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