英语周报高二外研42期答案2021-2022

24.【答案】(共12分)见解析解析】(1)设物块在水平面上的速度为v,根据机械能守恒有R(2分)解得:0=√2gR(1分)(2)设物块b的质量为m,碰撞后a的速度为v,物块b的速度为2,根据动量守恒定律有m0=m1+m2(2分)根据能量守恒有:m3=m2+m2……(2分)设物块b到达D点的速度为吗,根据牛顿第二定律有mg=mR…………(2分)根据机械能守恒定律有:m)m咬、m…………(2分)解得:m=(2①0-1)m…(1分)

第二节One possible versionDiamond hurriedly ran to the bird. Approaching thebird. he ran around themelt the bird. and thenbarked at his master. Gunnar understood the boy was asking him to help the bird. So, he picked it up gently. Aftercareful examination, Gunnar told his boy that Bibi didn'tlf indoors Considering that the bird wasn't wellgH to leave, he put him back in the basket, with andded bite of sweet potato as well. He decided to set himfree the next day, when he would be fully recoveredAfter Bibi s recovery, Gunnar placed him back out onthe balcony. Suddenly, the bird started to sing, as if hewere expressing thanks to Diamond. Then he spread hiswings,flying away. A while after the bird had gone, Isaid to Diamond: Where is Bibi?'"recalled GunnarHe looked at me, very sharply, then jumped on the sofaand ran directly to the balcony door. He knew exactly whatI was talking about.

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