本题目来源于试卷: Physics Unit9: Static Equilibrium, Elasticity and Fracture，类别为 国际高中通用物理
[单选题]
A uniform meter stick is p8ym3 9sc/ d yt,eg9fpd.4hbvsupported by9 o5/y zkhe7yc a knife edge at the 50-cm mark and has masses of 0.40 kg and 0.60 kg hanging at the 20-cm and 80-cm marks, respectivel o59/czy7kyhey. Where (at what mark) should a third mass of 0.30 kg be hung to keep the stick in balance?
A. $20 \; cm$
B. $25 \; cm$
C. $30 \; cm$
D. $70 \; cm$
参考答案: C
本题详细解析:
暂无
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