英语掌上周报2018-2022答案

One possible versionSeveral minutes later, the ice broke suddenly and Harry's feet sank into the water. It was noep, but his legs got wet to the knees. Harry was so upset that the accident would delay hisschedule. He had to find some firewood to build a fire to dry his clothes. He pulled off his glovestook out his matches, and lighted the fire. Seeing the burning fire, he had thought he was safe. Butsuddenly, without warming, a heavy mass of snow dropped down. The flame of hope was put outUnluckily, his dog ran away and the fear of death came over Harry. He had no choice but torun to save himself. However, he did not feel his feet when they hit the ground. Having falleneveral times, he decided to rest a while. As he lay in the snow, he noticed he was not shaking. Hecould not feel his nose or fingers or feet. A feeling of horror came into his mind. It was when herealized he was going to die that he heard a bark and the noise his friends made

14(1)22.0(2分)(4)m√1-c0sa=m√1-cs-m√1-cos(3分)m1cosa=m1cosB1-m2(1-cos62)(3分)【解析】(1)由题图乙可知,直径d=2.2cm+0.1×氵0mm=2.20cm=22.0mm。(4)设悬点到球心的长度为L,由动能定理可得mgL(1-cosa)=mt2,则小球A到达最低点时的速度大小v=√2gL(1-csa),同理碰后小球A的速度大小v1=√2gL(1-cos6),碰后小球归的速度大小v2=√2gL(1-cos2);若两小球碰前动量守恒,则表达式m1v=m2n-m1vh成m√2gL(1-cosa)=m2√2gL(1-cost2)m1√2gL(1-cos6)成立,故要验证两小球碰撞前、后动量是否守恒,需验证m1√1-csa=m2√1-cos6-m1√1cos6是否成立d若碰撞是弹性碰擅,则还应满足的表达式为2m1V子m十m远,即方m1(√2L(1-8a)2=2n2(√2gL(1-cosa2))2+2(√2gL(1-os))2,化简得m10sa≈氵m, cos 0,-m2(1-cos 82)

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