3) 瞎貓死鼠解.

來源: 於 2011-09-18 08:16:45 [舊帖] [給我悄悄話] 本文已被閱讀：次

Stone is mg on the face and 0 in the center. So,in side,the near center the lighter,linearised,F(x)=x/R*mg,...We get the same answer.