AL physics 問答區 [復制鏈接]

D9 dQ = dU + dW
thermodynamics??

From HL Tam Notes,
dQ = energy added to gas by heating
dU = increase in internal energy
dW = work done BY gas

下面是引用傷心小sam於2006-04-16 19:55發表的:
有野問ar~
考試局係咪唔接受"Q=U+W" ga?
e+係咪一定要用U=Q+W ga?
.......

唔知佢接唔接受ar ~
不過我睇 joint-us solution 就係用 Q=U+W 多

佢地分別就係在於W ge 正負~
例如你set W 係 system on the gas
條式就係 U = Q+W, 當gas compress 果陣, 即係周圍比 workdone 佢\
W 係正 , expand 果陣 W ===> - W ===> U=Q+(-W) ===> Q=U+W

如果你set W 係gas on system , Q=U+W
gas compress 同 expand 果陣條式同上

我就有另外2個問題
磁浮果陣, act on ring ge magnetic force independent of height ,
係未因為assume 左 magnetic flux 起 coil 上面都仲係當係直線,所以就算 個ring上d 佢所接收倒ge flux 都係一樣 ?

又有問題, polarization 入面 unpolarized light入glass block , refracted light 係 partially polarized
定unpolarized

下面是引用Arreat Summit於2006-04-16 23:19發表的:
又有問題, polarization 入面 unpolarized light入glass block , refracted light 係 partially polarized
定unpolarized

From the case of Brewster's angle, the reflected ray is partially polarized

the question above this one i answer tmr, gotta search search AL text sin

下面是引用kylau於2006-04-16 22:21發表的:
D9 dQ = dU + dW
thermodynamics??
From HL Tam Notes,
dQ = energy added to gas by heating
.......

我地都係教呢個ar~
但係ken chan就話唔俾用wor....
要用dU=dQ+dW ar~

下面是引用Arreat Summit於2006-04-16 22:37發表的:
唔知佢接唔接受ar ~
不過我睇 joint-us solution 就係用 Q=U+W 多
.......

即係2條式ge分別就在於W?

Q=U+W ge話，當dV increase，dW就係正ar ma
(即係workdone by gas)
(呢個我知)

咁U=Q+W，就係dV decrease果陣，dW係正??
(workdone on gas)

下面是引用傷心小sam於2006-04-17 15:53發表的:
即係2條式ge分別就在於W?
Q=U+W ge話，當dV increase，dW就係正ar ma
(即係workdone by gas)
.......

yes

on gas 同埋 by gas 的分別

btw, magnetic flux 個題我唔識, 都忘記得一乾二淨了.......

下面是引用傷心小sam於2006-04-17 15:53發表的:
即係2條式ge分別就在於W?
Q=U+W ge話，當dV increase，dW就係正ar ma
(即係workdone by gas)
.......

係~
果陣係system 比左workdone gas , 令到佢decrease , W 係正

明白！
thx~

arreat summit你果2條咁刁鑽ge.......
唔識ar......

polarization 果題我已經知道點解la , partially polarize 同unpolarize都可以形容refracted light
我nee個問題黎自joint us 85 年第20題MC ge solution ,果度答案應該係錯ge ~
另一點要留意ge就係, 連reflected light 都可以用partially polarized去describe ~或者partially plane-polarized ,marking 係accept ge

仲有magnetic flux 我同d同學講過,應該係有個uniform magnetic flux ge assumption ~
因為height 其實好細,影響唔大~

另一個新問題好細微細眼 , displacement of sound wave leads air pressure 定 lags air pressure ? beyond 2000 係 air pressure leads sound wave by "pi" /2, 我補習果度就調轉

你都讀得好detail好deep

我都忘記了.....

下面是引用kylau於2006-04-18 23:46發表的:
你都讀得好detail好deep
我都忘記了.....

其實有d問題係我見人地問,我自己又唔識,所以先起度問下~
我自己就冇睇過beyond 2000 ,連本書都冇,係人地講

睇完Arreat Summit d問題.........我好驚phy............~_~

下面是引用☆小強★於2006-04-18 23:50發表的:
睇完Arreat Summit d問題.........我好驚phy............~_~

其實有d太detailed , 好似磁浮果d 甘, 考試真係應該唔會點出, mc都係見過一題 ,我純粹個人想知下 .........