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 is60fa611ee8cb3.jpg, where m is the mass of the object and r is its radius.) Figure 1: Figure for problem 6. Figure 2: Figure for problem 7.60fa6141b5814.jpg60fa616069bd6.jpg

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統計: A(1), B(2), C(0), D(0), E(0) #2740284

詳解 (共 2 筆)

#4966922
 把2/5 mr2 ,當作額外的0.4E...
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#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
6a48ebc62bede.jpg
6a48ebda70a58.jpg
題目給實心球,所以代I=2/5mr^2
滾動不打滑,我們代v=rw
6a48ec14b1b68.jpg
能量守恆+最高點最低速度
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