6. A solid spherical marble starts from rest and rolls without slipping on the loop-the-loop track in fgure 1. What is the minimum starting height h from which the marble will remain on the track through the loop. Assume the marbles radius is small compared with R.
(A) 2.5R;
(B) 2.7R;
(C)2.9R;
(D) 3.1R;
(E) 3.3R.
(Note: the moment of inertial for a solid spherical object is
, where m is the mass of the object and r is its radius.) Figure 1: Figure for problem 6. Figure 2: Figure for problem 7.

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統計: A(1), B(2), C(0), D(0), E(0) #2740284
統計: A(1), B(2), C(0), D(0), E(0) #2740284
詳解 (共 2 筆)
#7430202
所以這題是滾動小球過垂直圓環
1.小球不能在最高點掉下來
2.小球是滾動,所以能量不只平移動能還有轉動動能


題目給實心球,所以代I=2/5mr^2
滾動不打滑,我們代v=rw

能量守恆+最高點最低速度

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