本题目来源于试卷: Quantum Mechanics of Atoms，类别为 IB物理学
[单选题]
Would it ever be possible to bal(q.er- )nckuk(9e8uw lk.zkaance a very sharp needle precisely jw4m zci5f:f8 on its point? Explain.f 8:5z4 miwjcf
A. yes
B. no
参考答案: B
本题详细解析:
No, it would not be possible to bal74(fvmb 4if0q 0 hvimyance a very sharp needle precisely on its point. Both the center of mass of the needle and the point of the needle cannot be precisely known, especially when speed and momentum are small. If we don’t know exactly where they are, but we ne44v qm7b vf00f ihi(ymed the center of mass directly above the point to balance, it is not possible. Also, the speed and momentum of both the center of mass and the point cannot be precisely known, especially if we think we know their positions exactly. Thus, if we do know that the center of mass and the point lined up exactly, then we couldn’t also know that they are both not moving, and it would fall over.
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