tabogirl910 2010-7-30 10:07 AM
phy mc 97 #1
唔明點解MARKING會寫 for A to move , T>=f_A ............
問題都冇話A會郁, 又點for A to move ?
steven_1115 2010-7-30 11:27 PM
B move，A相對B就會MOVE！:)
tabogirl910 2010-7-30 11:32 PM
回覆 #2 steven_1115 的帖子
that's mean 唔係堅郁,係相對B黎講有郁
right?
steven_1115 2010-7-30 11:38 PM
佢都可以話喺堅move
因為跳繩是不可延伸的（ i guess so),
B向左移動，連住A條繩會拉佢去右邊！
呢度喺想考，兩個物體之間都有摩擦力
tabogirl910 2010-7-30 11:47 PM
[quote]原帖由 [i]steven_1115[/i] 於 2010-7-30 11:38 PM 發表 [url=http://lsforum.net/board/redirect.php?goto=findpost&pid=2272049&ptid=146063][img]http://lsforum.net/board/images/common/back.gif[/img][/url]
B向左移動，連住A條繩會拉佢去右邊！[/quote]
but T 要大過摩擦力,A先堅郁.....
但冇話T 係大過摩擦力...
我唔知岩5岩...
steven_1115 2010-7-30 11:50 PM
2+ 問你若果B可以move，T最細會喺幾多，甘個T就一定=最大摩擦力
tabogirl910 2010-7-30 11:53 PM
回覆 #6 steven_1115 的帖子
係問F最細會喺幾多
kiwakwok 2010-7-31 12:16 AM
Hope that it helps
[attach]28543[/attach]
Note: After applying F, B moves to the left and A moves to the right. (The string is assumed to be inextensible and with negligible mass.)
kiwakwok 2010-7-31 12:21 AM
回覆 #5, #7 tabogirl910 的帖子
The question is asking you to find out the minimum force that sets B into motion.
That is, B needs to move to the left and in turn A needs to move to the right.
For A to move, T needs to be a little bit greater than the friction in magnitude.
Therefore, minimum T = 2N.
tabogirl910 2010-7-31 12:21 AM
fmax is 2 N 係咪姐係可以細過OR=2N ?
steven_1115 2010-7-31 12:23 AM
Tmin=2N,not max
kiwakwok 2010-7-31 12:24 AM
回覆 #10 tabogirl910 的帖子
f[subtag]max[/subtag] = f[subtag]s, max[/subtag] = 2N
=> Just a little bit greater than 2N will set the block into motion. Therefore, we take 2N.
tabogirl910 2010-7-31 12:27 AM
回覆 #9 kiwakwok 的帖子
呢個明~~:)
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