[S]Mangoray 發表於 4-10-2008 13:22:11

mechanics

http://i350.photobucket.com/albums/q437/mangorayyau/1.jpg


q28點做??

看不清請到
http://i350.photobucket.com/albums/q437/mangorayyau/1.jpg

Zend 發表於 4-10-2008 14:08:19

好似做過, 係take moment , about 個轉動點
唔多記得la

[S]Mangoray 發表於 4-10-2008 14:23:56

a部答案是40N[]

piyopiyo 發表於 4-10-2008 15:11:33

對Q29較有興趣[]
29a是否30N[]

[S]Mangoray 發表於 4-10-2008 17:29:22

原帖由 piyopiyo 於 4-10-2008 15:11 發表 http://www4.nakuz.com/bbs/images/common/back.gif
對Q29較有興趣[]
29a是否30N[]

係阿,點解係30N,而唔係70N[] ?

piyopiyo 發表於 4-10-2008 17:34:50

let T1,T2,T3,,,T1係最低果個pulley ge tension against the 21kg mass,,,so on so forth

As they are in equilibrium,,,T1 = F
T2 = F+T1 = 2F
T3= T2 + 2F = 4F
T1+T2+T3 = 210
7F=210
F=30N[]

[S]Mangoray 發表於 4-10-2008 17:48:47

原帖由 piyopiyo 於 4-10-2008 17:34 發表 http://www4.nakuz.com/bbs/images/common/back.gif
let T1,T2,T3,,,T1係最低果個pulley ge tension against the 21kg mass,,,so on so forth

As they are in equilibrium,,,T1 = F
T2 = F+T1 = 2F
T3= T2 + 2F = 4F
T1+T2+T3 = 210
7F=210
F=30N[]

[]厲利厲利


至於q28

(a) Take moment at the point where the wheel touches the kerb,
50 x [(1+0.2-0.5] = W x
W=40N
where W is the weight of the wheel


可唔可以解一解個答案[] ??

Puppet 發表於 4-10-2008 17:58:41

原帖由 Mangoray 於 4-10-2008 17:48 發表 http://www1.nakuz.com/bbs/images/common/back.gif


[]厲利厲利


至於q28

(a) Take moment at the point where the wheel touches the kerb,
50 x [(1+0.2-0.5] = W x
W=40N
where W is the weight of the wheel


可唔可以 ...
first, do u know what square-root(1^2-0.5^2) is?

[S]Mangoray 發表於 4-10-2008 18:06:27

原帖由 Puppet 於 4-10-2008 17:58 發表 http://www1.nakuz.com/bbs/images/common/back.gif

first, do u know what square-root(1^2-0.5^2) is?

我唔明點解 W 同 F 成直角都有MOMENT

Puppet 發表於 4-10-2008 18:08:46

原帖由 Mangoray 於 4-10-2008 18:06 發表 http://www1.nakuz.com/bbs/images/common/back.gif


我唔明點解 W 同 F 成直角都有MOMENT
你解下點解W 同 F 成直角應該冇MOMENT先
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