查看完整版本 : Science 問題,求救

旋風仔仔 2016-10-22 11:09 PM

Science 問題,求救

這2題點計,老師未教就叫我哋做,唔識做,求各位Ching教教小弟[attach]6094970[/attach]

hkpal 2016-10-23 12:42 AM

用 action = reaction
想想每條桁架/繩索的抗力/拉力的方向是怎樣的.

旋風仔仔 2016-10-23 01:38 AM

[quote]原帖由 [i]hkpal[/i] 於 2016-10-23 12:42 AM 發表 [url=http://www.discuss.com.hk/redirect.php?goto=findpost&pid=450247213&ptid=26185673][img]http://www.discuss.com.hk/images/common/back.gif[/img][/url]
用 action = reaction
想想每條桁架/繩索的抗力/拉力的方向是怎樣的. [/quote]
版主大人,仲有一條求指教[attach]6095438[/attach]
[attach]6095439[/attach]
7a,b識計,但c,d,e點計求指教小弟

hkpal 2016-10-23 02:28 PM

Q7
(a) Take moment about the fulcrum.  Recall moment = force x distance = mg x d.
(b) Use similar triangles or by proportional distance.
(c) Work done = Force x Distance moved
(d) Read http://www.citycollegiate.com/machine1.htm
(e) Probably due to the 60N force

Q8
There are TWO cords and their tensions need not be the same.
Write T as tension in cord B and T' the tension in cord A.
Your first equation is correct, but you need to adjust your second equation to calculate T'.

旋風仔仔 2016-10-23 04:05 PM

[quote]原帖由 [i]hkpal[/i] 於 2016-10-23 02:28 PM 發表 [url=http://www.discuss.com.hk/redirect.php?goto=findpost&pid=450273410&ptid=26185673][img]http://www.discuss.com.hk/images/common/back.gif[/img][/url]
Q7
(a) Take moment about the fulcrum.  Recall moment = force x distance = mg x d.
(b) Use similar triangles or by proportional distance.
(c) Work done = Force x Distance moved
(d) Read http://www ... [/quote]
感謝版主大人指教🙇🏻🙇🏻🙇🏻
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查看完整版本: Science 問題,求救