phy~從不知怎麼是對的

unlock-YM · 發表於 3/4/2010 07:49 PM

咁有咩時候a唔係constant架??(cert level黎講)
好似冇乜!?
小霞的fans 發表於 3/4/2010 07:16 PM

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應該係冇。

小霞的fans · 發表於 5/4/2010 10:54 AM

本帖最後由小霞的fans 於 4/4/2010 02:55 PM 編輯

問題:
   一一一
A l          l  C
___l          l___

A train of progressive waves travels from left to right.A同C區既深度係一樣...我想問點解A同C個wave form會唔一樣既~?唔係應該相同架咩?答案果度印呢..C區既wave既wavelength同A區一樣..不過C區個wave既高度短D..冇A區咁高..我想知點解-0-""
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[GW]赤沙 · 發表於 5/4/2010 12:26 PM

問題:
   一一一
A l          l  C
___l          l___

A train of progressive waves travels from left to right.A同C區既深度係一樣...我想問點解A同C個wave form會唔一樣既~?唔係應該相同架 ...
小霞的fans 發表於 5/4/2010 10:54 AM

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高度 = Amplitude
而Amplitude的大小代表wave process的energy
Wave随着propagation, energy 下降, Amplitude 所以 gradually decrease.
但Amplitude 應該同wave form 無關 ...?

小霞的fans · 發表於 13/4/2010 11:44 AM

高度 = Amplitude
而Amplitude的大小代表wave process的energy
Wave随着propagation, energy 下降, Amplitude 所以 gradually decrease.
但Amplitude 應該同wave form 無關 ...?
赤沙發表於 4/4/2010 04:26 PM

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咁我想問問diffraction,,reflection 會唔會有energy loss架!?
佢地既amplitude都會gradually decrease?? thanks~

inthomaspy · 發表於 15/4/2010 01:04 AM

咁我想問問diffraction,,reflection 會唔會有energy loss架!?
佢地既amplitude都會gradually decrease?? thanks~
小霞的fans 發表於 13/4/2010 11:44 AM

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During reflection, there should have no energy loss
During diffraction, there will also have no energy loss but it leads to change in direction of wave propagation and re-distribution of energy. That is, some energy in the original wave are distributed to the 'bended' side of the diffracted wave.
  ︱          \       << some original energy is distributed here
  ︱          ︱
  ︱          ︱
  ︱          ︱
  ︱          /       << some original energy is distributed here
The amplitude of the wave will decrease gradually as it travels because there will be resistance and hence energy is lost to the surrounding

囧囧中自有囧囧 · 發表於 15/4/2010 03:09 AM

某中五會考生路過
今星期先開始溫錯唔好插-︿-
TROLLEY個題
FAN會左吹推AIR向左 AIR推番TROLLEY向右
向左GE AIR 撞到CARBOARD 推CARBOARD令TROLLEY向左
CARBOARD推番AIR向右
AIR 向左同向右GE力抵消(?!
TROLLEY向左向右GE力相同所以唔旭掛
可能錯-,-
the variation of kinetic energy with time.
a=gsin x
g costant a constant
m constant
k.e vary with t^2
=====================================
wave length of visible violet light in glass is greater than that in air.應該係錯
v =f x (wavelength)
v in glass decrease frequency不變
wavelength decrease 唔太記得係唔係咁解囧rz
=======================================
ce 好似assume左air個係1同vacuum一樣
v of E.M.wave 係光速in air
========================================
話說第二題唔係應該係
T+(mg)=ma
g係negative所以係
T-mg=ma咩
點解係T+mg=ma囧
=========================================
time interval個幾題係take 5個點中間個位計好似係-_,-唔記得囧

小霞的fans · 發表於 15/4/2010 03:05 PM

本帖最後由小霞的fans 於 14/4/2010 08:37 PM 編輯

violet visible light係glass既speed慢d定red visible light慢d架!?
書裡面冇提過但係past paper出過!?
同埋呢..
T+(mg)=ma
g係negative所以係
T-mg=ma咩
點解係T+mg=ma囧

點解係+既.....

囧囧中自有囧囧 · 發表於 15/4/2010 09:33 PM

本帖最後由囧囧中自有囧囧於 15/4/2010 11:42 PM 編輯

呀sir話係glass ,red light快過violet
但係wavelength of violet細過red

ice · 發表於 15/4/2010 11:11 PM

呀sir話係glass ,red light快過violet
但係wavelength of violet大過red唔記得點解lu
囧囧中自有囧囧發表於 15/4/2010 09:33 PM

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不是frequency ofviolet>frequency ofred
wavelength ofviolet<wavelength ofred嗎

囧囧中自有囧囧 · 發表於 15/4/2010 11:42 PM

更正囧我抄錯野--呀sir話係glass ,red light快過violet
wavelength of violet<wavelength of red先岩囧rz
i am so sorry

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[求助] phy~從不知怎麼是對的