本题目来源于试卷: 2012美国US F=MA物理竞赛，类别为 美国F=MA物理竞赛
[单选题]
An equilateral triangle is sittingtdy 9bnsj 0x15 qly(q* on an inclined plane. Friction is too high bxbdt:clv q 4p0 t+b21for it to slide under any circumstance, but if the plane is sloped enough it can "topple" down the hill. What angle incline is necessary forb0bxltv: 4bp +c 1q2dt it to start toppling?
A. $30$ degrees
B. $45$ degrees
C. $60$ degrees
D. It will topple at any angle more than zero
E. It can never topple if it cannot slide
参考答案: C
本题详细解析:
Toppling occurs when the vertical line passing through the object's center,m(imoy9l5vg8eai:p m fba p 3x/46a e of mass (CM) falls outside its base of support. For an equ/p:vambxmplie9g mf5 y,4ea ( o638ai ilateral triangle, the CM is at its geometric center. It will topple about its lower corner. The angle from the base to the line connecting the CM and the corner is $60^\circ$. When the incline angle equals this angle, the CM is vertically aligned with the pivot point, and any further increase will cause it to topple.
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