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16??????????????d=2m???AB???????????h=1m????????????????g?10m/s2?
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20??9?? ???????R = 0.4m?????????????????A????
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???
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25??13?????????m?1 kg???????????l?0.5 m?????????F?18 N??????.????????????????????????????.?????????????h?5 m??????g?10 m/s2????????????????.?P?????????
28?????????2kg?????0.4m?????????????
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29?????10m/s??????????????????50m???????????60kg??????????
3
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发表于 2019-9-13 23:46:11