4. A block of mass m sliding down an incline at constant speed is initially at a height h above the ground, as shown in the figure. The coefficient of kinetic friction between the mass and the incline is μ.If the mass continues to slide down the incline at a constant speed, how much energy is dissipated by friction by the time the mass reaches the bottom of the incline?5eeade85d82b2.jpg
(A) mgh/µ
(B) mgh
(C) µmgh/ sin θ
(D) mgh sin θ
(E) 0

答案:登入後查看
統計: A(1), B(55), C(3), D(2), E(1) #2356580

詳解 (共 3 筆)

#4154574
 動能沒有變化,損失的力學能為損失的位能...
(共 28 字,隱藏中)
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3
0
#4744380
非保守力做功=力學能變化 初末速度不變 ...
(共 34 字,隱藏中)
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2
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#6181301

如果認真算

經過一番努力會得到摩擦力Fk(Fk=Miu.mgCos日)以定力做功距離d(d=h/sin日)的功W
W=Miu.mgh(Cos日/Sin日)
然後沒有答案
代表這題想考的是定義
物體物體的能量從A點到B點只有損失位能Mgh(因為題目說速度不變代表動能沒改變)
結束

0
0