如果初始铁棒几乎躺着，剪断瞬间支撑力还是重量吗？
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送交者: gyro 于 2009-09-17, 14:48:41:
回答: 困惑在哪里？也别微小偏差了，就干脆垂直，剪断瞬间支力就是全部重力。 由 chouqilozi 于 2009-09-17, 14:44:15:
Strictly vertical position is in equilibrium. You have a fairly long time window in which the supporting force is equal to mg.
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