作者deepwoody (快回火星吧)
看板Physics
标题[问题] 普物一题
时间Wed Feb 17 23:27:22 2010
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
我的疑问：
设摩擦力为f，那麽合力矩 τ= f*R2－T*R1 = I'α
这个转动惯量I'，我觉得应该要换成I+m(R2)^2才合理
但是我手边的详解却是直接把I'以I(题目所给，也就是转轴穿过CM的转动惯量)来代
考虑滚动的时候，转动惯量不是应该要修正吗?
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※ 编辑: deepwoody 来自: 218.169.100.27 (02/17 23:29)
1F：→ SmArTyau:你修正转动轴时,力与力臂的关系不需要改吗? 02/18 01:27
2F：→ deepwoody:那这个物体是不是就不是"滚动"了呢 02/18 08:54
3F：推 chieh0206:你f和T都是以转轴当支点算力矩,所以I也要用中心转轴 02/18 16:32
4F：→ deepwoody:谢谢，我懂了 02/18 17:48