[問題] 普物一題

看板Physics作者deepwoody (快回火星吧)時間14年前 (2010/02/17 23:27)推噓1(1推 0噓 3→)

留言4則, 3人參與討論串1/4 (看更多)

A spool of thread consists of a cylinder of radius R1 with end caps of radius R2 as shown in the end view illustrated in Figure P10.77. The mass of the spool, including the thread, is m, and its moment of inertia about an axis through its center is I. The spool is placed on a rough horizontal surface so that it rolls without slipping when a force T acting to the right is applied to the free end of the thread. Show that the magnitude of the friction force exerted by the surface on the spool is given by ┌ I + mR1R2 ┐ f = │──────│T └ I + m(R2)^2┘ http://tinyurl.com/ye37j4l 我的疑問：設摩擦力為f，那麼合力矩 τ= f*R2－T*R1 = I'α 這個轉動慣量I'，我覺得應該要換成I+m(R2)^2才合理但是我手邊的詳解卻是直接把I'以I(題目所給，也就是轉軸穿過CM的轉動慣量)來代考慮滾動的時候，轉動慣量不是應該要修正嗎? -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 218.172.249.14 ※ 編輯: deepwoody 來自: 218.169.100.27 (02/17 23:29)

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