[問題] 有關於一題物理

[chenkaihsu (Shrek)]

A 65kg  bungee jumper leaps from a bridge.
She is tied to a bungee cord that is
12 m long when unstretched, and falls a total of 31m .
Calculate the spring constant k  of the bungee cord assuming Hooke's law
applies.
我ㄉ解法是 (31-12)/65*g這樣錯了嗎??答案不是這個耶......幫我解釋一下??

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→ SmArTyau:用能量守衡去算吧? mgh+0+0=0+(1/2)kx^2+0
→ SmArTyau:k=2mgh/x^2=2*65*g*31/19^2=11.16g
→ chenkaihsu:the answer is not 11.16..@@
推 tatty:他後面還有個g耶........你確定你有看清楚嗎?
→ chenkaihsu:sorry iam wrong.....我沒看到gggg