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发表于 18-3-2009 12:24 PM
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回复 163# hihi23 的帖子
我不是很明白这个问题的concept..
如果initial 的pressure of two vessel 是不一样呢？
或是initial的 temperature of two vessels 是不一样的。。
还能算的吗？
我先说谢谢。。。  |
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发表于 18-3-2009 12:43 PM
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是不是说把 initial 的放在一起。。 final 的放在一起。。
然后用 mole 是一样的concept , 就可以solve? |
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发表于 14-5-2009 09:21 PM
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发表于 20-5-2009 06:43 PM
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1. The air resistance ,F on a vehicle depends on the velocity,v of the vehicle,the density of air,ℓ and the cross-sectional area of the vehicle,A.
Derive an expression which relates F,V,ℓ and A.
2. The period of oscillation,T of a drop of liquid is given by the formula T=ka^xℓ^yγ^8 where k is a dimensionless constant,a is the radius of the drop ,ℓis the density andγ is surface tension of the liquid with dimension MT^-2.Determine the actual formula by using dimension analysis.
请高手帮忙解答！！！ 谢谢！！！ |
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发表于 24-6-2009 09:38 PM
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原帖由 笨蛋一个 于 12-2-2009 01:04 PM 发表 
你是指F=GMm/r^2?
那个formula不是proof来的
而是experiment和观察做出来的结果
听说好像是做梦时周公跟他说的
周公说的就没有听说过
不过,都是ｐｒｏｐｏｒｔｉｏｎａｌ的东西 |
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发表于 28-6-2009 04:24 PM
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回复 167# liauzh 的帖子
2. T=k a^x ℓ^y γ^8
is the power of γ = z ? I do the question according to z.. because acc. to 8, cannot do..
[T]=k [a^x] [ℓ^y] [γ^z]
s = (m ^x) [(kg m^-3)^y] [(kg s^-2)^z]
s = kg ^ (y+z) m ^(x-3y) s ^-2z
-2z = 1
z = -1/2
y+z =0
y = 1/2
x-3y = 0
x =3/2
Hence, T=k a^(3/2) ℓ^(1/2) γ^(-1/2)
Please correct me if i did wrong. Thank you |
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发表于 28-6-2009 04:41 PM
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回复 167# liauzh 的帖子
1.Let F =V^x ℓ^y A^z
[F] =[V]^x [ℓ]^y [A]^z
kg m s^-2 = (m s^-2)^x (kg m^-3)^y (m^2)^z
kg m s^-2 = kg^y m^(x-3y+2z) s^-x
y = 1, x =2, 2-3+2z= 1
z = 1
Hence, the formula would be F =V^2 ℓA |
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发表于 13-7-2009 09:20 PM
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what are the question might come out this year? |
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发表于 24-7-2009 10:02 AM
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不好意思，我想请问物理第一课的那四个velocity的equation是什么？我需要用到却忘了。 |
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发表于 24-7-2009 08:13 PM
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linear motion law:v=u+at v square=u square+2as s=0.5{u+v}t s=ut+0.5atsquare |
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发表于 25-7-2009 12:19 AM
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介绍大家Federal的练习书 |
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发表于 5-8-2009 03:55 PM
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发表于 7-8-2009 07:23 PM
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发表于 8-8-2009 02:35 PM
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原帖由 歆 于 7-8-2009 07:23 PM 发表
哦。。那有什么好介绍呢？
本人现在用着federal的
hm.....雖然很多 out of syllabus de.. 不過我覺得federal 的還是最好的.. |
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发表于 8-8-2009 03:42 PM
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原帖由 Dicardo 于 8-8-2009 14:35 发表 
hm.....雖然很多 out of syllabus de.. 不過我覺得federal 的還是最好的..
哈哈，原来。。。 |
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发表于 8-8-2009 03:58 PM
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原帖由 歆 于 8-8-2009 03:42 PM 发表
哈哈，原来。。。
哦，對了。。
我那過federal的chemistry 去問老師，她說裏面很多都是新加坡的syllabus... |
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发表于 8-8-2009 05:04 PM
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原帖由 Dicardo 于 8-8-2009 15:58 发表
哦，對了。。
我那過federal的chemistry 去問老師，她說裏面很多都是新加坡的syllabus...
我倒是没用federal的chemistry |
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发表于 9-8-2009 12:20 AM
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其实说op-amp是perform mathematical functions是不是说它是一个计算机之类的东西？然后怎样做出什么加减乘除的程式？很不理解耶，最后又没有说到怎样做出加减乘除还是例子的，很模糊地说。
有谁能帮忙我这个物理白痴解答吗？ |
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发表于 9-8-2009 12:57 AM
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回复 181# idontwant2b 的帖子
只有一个concept----> voltage output不能大过voltage input |
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发表于 20-9-2009 06:03 PM
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请大家帮帮忙。。小弟感激不尽。。。...
a proton with mass 1.67x10^27 is propelled at an intial speed of 3.00x10^5 ms^-1 directly towards a uranium nucleus 5.00mm away.the proton is repelled by the uranium nucleus with a force of magnitude F=a/x^2,where x is the separation between two objects and a =2.12x10^-26 Nm^2. assume that the uranium nucleus remains at rest .
question:what is the speed of the proton when it is 8.00x10^-10 m from the uranium nucleus?
question:as the proton approaches the uranium nucleus,the repulsive force slows down the proton until it comes momentarily to rest , after which the proton moves away from the uranium nucleus. how close to the uranium nucleus does the proton get?
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