一滑輪裝置如附圖﹐W在開始運動後4秒內行徑19.6m之距離﹐則W重為(A)15kg (B)12kg (C)9kg (D)6kg
圖片參考：https://s.yimg.com/rk/AB00132372/o/265017412.jpg
Ans: 12kg (不知答案是否有誤?我算出為6kg)
請物理高手們,幫忙詳解,謝謝!!!
基礎物理----力學一問,求詳解!
2014-04-16 1:00 am
回答 (14)
2014-04-16 3:09 am
✔ 最佳答案
基礎物理----力學一問,求詳解!.牛頓運動公式: Vo=0L=Vo*t+a*t^2/2 => 19.6=8aa=19.6/8=2.45(m/s^2)ΣFx=T-10*9.8*0.2=10*a => T=19.6+24.5=44.1(N)ΣFy=W-T=(W/g)*a => W(g-a)/g=TW=T*g/(g-a)=44.1*9.8/(9.8-2.45) N=44.1/7.35=6(kg)......ans=(D)
2014-05-08 3:44 pm
2014-05-02 3:00 pm
2014-05-01 4:49 pm
2014-04-30 10:16 pm
2014-04-29 3:43 pm
2014-04-27 10:32 pm
2014-04-25 2:26 pm
2014-04-16 3:44 am
題目問物重，選項單位卻是質量
2014-04-16 3:07 am
a=(w-0.2*10g)/(w/g+10)
(at^2)/2=2g=>a=g/4
g/4=(w-0.2*10g)/(w/g+10)
(w-2g)=g/4*(w/g+10)=w/4+5g/2
=>3w/4=9g/2
=>w=6g
(at^2)/2=2g=>a=g/4
g/4=(w-0.2*10g)/(w/g+10)
(w-2g)=g/4*(w/g+10)=w/4+5g/2
=>3w/4=9g/2
=>w=6g
參考: My brain
收錄日期: 2021-05-02 11:09:06
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20140415000010KK05721