推 chenkaihsu:還是不太懂,,,,,可以說明一下嗎?? 11/02 11:43
→ Dirac5566:他第二條是彈回來的能量消耗 11/02 13:50
推 su3g45j:你不懂？代表撞一次所需的能量 11/02 19:21
※ 引述《chenkaihsu (Shrek)》之銘言：
: [領域] 大一普物 (題目相關領域)
: [來源] 課本 (課本習題、考古題、參考書...)
: [題目] An object of mass m is traveling on a horizontal surface. There is a
: coefficient of kinetic friction 摩差係數b between the object and the surface. The
: object has speed v when it reaches x=0 and encounters a spring. The object
: compresses the spring, stops, and then recoils and travels in the opposite
: direction. When the object reaches x=0 on its return trip, it stops.
: Find k in terms of b mg v
: [瓶頸] (寫寫自己的想法，方便大家為你解答)
: 我列式出來是 1/2*mv^2=bmgd+1/2*kd^2(設d為壓縮距離)但我解不出來....有2ㄍ未知數
1/2*mv^2=bmgd+1/2*kd^2
1/2*kd^2 - bmgd = 0
=> d = 2bmg/k
=> k = 2bmg/d --------(1)
1/2*mv^2=2bmgd
=> d = 1/4 * v^2/bg代入(1)
=> k = 8 b^2g^2m/v^2
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◆ From: 122.124.102.144
※ 編輯: Honor1984 來自: 122.124.102.144 (11/02 00:17)