7. A rectangular block twice as high as it is wide is resting on a board. The coefficient of static friction between board and incline is 0.46. If the board's incline angle is gradually increased,
(A) the block will first tip over than slide.
(B) the block will first slide than tip over.
(C) will the block first tip over or begin sliding depends on its moment of inertia.
(D) will the block first tip over or first begin sliding depends on the coefficient of kinetic friction between board and incline.
(E) None of the above.
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統計: 尚無統計資料
統計: 尚無統計資料
詳解 (共 3 筆)
#7407985
所以從滑動來推關係
物體在斜面上往下滑動,往下的重力分量為mgsincita
最大靜摩擦力為usmgcoscita
所以剛好要滑動時,mgsincita=usmgcoscita
除過去可以得到tancita=us
而us=0.46
接著算翻倒的
翻倒的臨界條件為tancita=高/底
所以為0.5
而我們去比誰的數值比較小會優先發生
所以滑動所需的摩擦力比較小,所以會優先發生
再來是翻倒
ㅤㅤ
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