neilhua 发表于 2010-2-20 02:52

有意思。没办法~~有意思。没办法~~
有意思。没办法~~有意思。没办法~~

funny_lp 发表于 2010-2-20 08:05

还好还好还好还好还好还好哈 $ J6 q& Z, K% ]; j  j3 L- e
啦啦啦啦

ml0872570 发表于 2010-2-20 08:24

这到底是反映什么的？？？~~~~~~~~

cpp0325 发表于 2010-2-20 08:29

跟MCM有什么关系吗?:(????????????????

cyj66 发表于 2010-2-20 09:21

太好了
1 h3 O9 @0 l) S0 P从现在开始我乱花钱- z6 Q" A) E* j! D' R
. w9 R, t+ B& Y. G. I+ H; D. N
呼呼
6 M# u0 e  \) [4 b; F- H. s总有一天我成为负翁的

lijingwen1989 发表于 2010-2-20 10:10

回复 1# william11211


    有意思！

lijingwen1989 发表于 2010-2-20 10:14

回复 11# neilhua


    好厉害！

zhouhuanjia 发表于 2010-2-20 10:28

hehe~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

ch71444 发表于 2010-2-20 11:20

The centre of percussionCOP is not a unique point on
the barrel since it is defined in terms of a conjugate point in
2,6,7
the handle. Each point in the handle is associated with a
different COP in the barrel. When a ball strikes a freely
suspended bat, the bat will translate in the direction of the
incident ball and it will also rotate about the centre of mass.
The combined effects of translation and rotation result in a
shift of the actual axis of rotation, away from the centre of
mass toward the handle. The axis passes through the conju-
gate point for that particular impact. If b is the distance from
the impact point to the centre of mass, and x is the distance
from the centre of mass to the conjugate point, then xIcm/(Mb) where Icm is the moment of inertiaof the bat
about its centre of mass and M is the mass of the bat. Con-
sequently, if the bat is pivoted about an axis through the
conjugate point, and if the ball strikes the corresponding
COP, then there is no reaction force at the pivot point. It is
therefore reasonable to expect that every point under the
hands will have its own COP and that an impact at any given
COP will generate zero reaction force at the corresponding
8
conjugate point under the hands. Brancazio has suggested
that the sweet spot zone might therefore encompass all cor-
responding COP points along the barrel. There is, however,
an uncertainty in this argument since a hand-held bat is not
freely suspended, nor is it pivoted about a single axis, and
may behave differently as a result of the reaction forces ex-
erted by the two hands. Furthermore, the axis of rotation may
even shift as a function of time since the ball remains in
contact with the bat for about 1.5 ms, the transmission time
of the pulse from the impact point to the hands is about 1 ms,
and the impact forces on the hands last for about 20 ms as a
result of the induced vibrations and the induced motion of
the bat.

ch71444 发表于 2010-2-20 11:21

呵呵，好的~~~~~~~~~~~~~~~~~~~~~~~~
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